Plates X., XI.The present paper contains descriptions of 4 new genera and 62 new species of South African Spiders contain eel in the Collection of the South African 1\'[useum.With the exception of 3 new species of PI'Q(Zidomidw, all of them belong to the groups Mygcblo1JlO1'Ph(1J (Migidce, 1 n. sp.; Cteniziclce, 1 n. gen. and 5 n. spp.; Barychelicl!J3, 2 n. spp.), Cribellat(1J (Uloboricl(1J, 1 n. gen. and 3 n. spp.; Dictynirlce, 4 n. spp.; Eresicl!J3, 6 n. spp.) , and Ecribellat(1J Haplogynce (Sicariicl(1J, 19 n. spp.; Dyscle1'iclce, 1 n. geu. and 11 n. spp.; CCbponiiclce, 1 n. gen. and 8 n. spp.).FAMILY MIGIDlE.
THE present paper contains descriptions of ten new species of Solpuga, and of five little known forms of the genus, which were described by Koch in 1842; further, four new species of Daesia, and three of Ceroma, both genera not previously recorded from South Africa, and one new species of Hexisopus. The male of the last-named remarkable genus is here described for the first time.The following is a synopsis of the South African genera :a. Tarsus of IV. leg without claws .. .. .. .. Hewisopus, Karsch (p. 381). 6. Tarsus of IV. leg with two claws. s Tarsi of II -IV. legs 2-jointed .. .. .. Ceroma, Karsch (p. aH . Tarsi of II-III. legs 2-jointed, of IV. leg fe Famed Daesia, Karsch (p. 388). . Tarsi of IIIT. legs 4-jointed, of IV. leg 7-jointed. Solpuga, Licht. (p. 401).
THE present paper deals with the South African species of Peripatidfe, as represented in the collection of the Museum. Pull descriptions of the external systematic characters of three out of the four previously described species (P. capensis, balfouri, and moseleyi) are given, together with descriptions of four new and perfectly distinct ones. In addition five other forms are recorded, hut not named, on account of lack of sufficient material.Historical. The genus Peripatus has been known from America since its first establishment by Guilding in 1826, and some years afterwards, in 1837, the first South African species was recorded and described by De Blainville as Peripatus brevis, with 14 pairs of legs.It was found by M. Goudot on Table Mountain, but appears never to have been met with since.Peripatus does not seem to have been recorded from South Africa again until 1868, when Grube described three specimens found under stones on a hill at Constantia by Bitter v. Frauenfeld, during the visit of the Austrian frigate " Novara " to the Cape in October, 1857. These three specimens were named Peripatus capensis by Grube, and possessed 17-18 pairs of claw-bearing legs. Two of these, including those figured, belong to Peripatopsis capensis as at present limited, while the third belongs to the species subsequently called balfouri by Sedgwick.Guilding placed Peripatus amongst the Mollusca, while Grube considered it to be an Annelid. It was not until the visit of the "Challenger" to the Cape in 1873, when Moseley obtained and dissected living specimens of P. capensis, that the tracheate character of these animals was discovered. Moseley obtained his specimens Purcell, W F. 1899. "On the South African species of Peripatidae in the collection of the South African Museum." Annals of the South African Museum.
It is just one hundred years ago that the first anatomical account of the lung-books of Arachnida was published by Meckel (‘09), who, like his immediate successors, looked upon these organs as gills, and it was not until 1828 that their pulmonary nature was recognised by Johannes Miiller (‘28a, ‘28b) and Straus-Durckheim (‘28). The latter was also, I believe, the first to point out (p. 315) that the lung-books could be regarded as a special form of tracheae, a view which was later on elaborated by Leuckart (‘48, p. 119 note, and ‘49) and for a time generally accepted, until the appearance of Ray Lankester’s paper,”Liraulus: an Arachnid,”in 1881, opened up the probability of the branchial origin of these organs.
The theoretical suggestions in the preceding paragraphs may be summed up as follows: In the first place I suppose the saccules of the second pair of lung-books to have been converted into tracheal tubules in the common ancestor of the Dysderidæ, Oonopidæ, and Caponiidæ. The resultant tracheæ then increased in size, and, as the number of the leaves of the anterior lungbooks decreased in inverse ratio, the former became the priucipal organs of respiration. The second pair of spiracles retained their position, or may even have moved slightly forwards, and the conversion oE the entapophyses into trachea? could not take place here, and would, moreover, be quite unnecessary. In the Caponiidaa the anterior pair of lungbooks were converted into tracheae in a similar manner, but at a, later period, and independently of the conversion of the posterior pair; but as the latter already provided almost the entire body with tracheæ, the anterior pair did not further increase in size. In the second place, iu the progenitor (or progenitors) of the remaining tracheate spiders, the posterior lung-books became reduced in size and effectiveness by the disappearance oE their saccules, accompanied by an increase in the number of the leaves of the anterior lung-books. Further, the posterior spiracles became approximated and united to a single spiracle, and moved towards the hinder end of the body, thereby causing the entapophyses of the tracheal segment to elongate. In this condition the Filistatidas, Sicariidse, and Palpimanidas have remained, with slight modifications, such as the division of the tracheal antechambers into branches in some forms. In the great majority of the families, however, the elongated entapophyses became transformed into a pair of medial tracheal trunks, thus producing a tracheal system consisting of four simple unbranched trunks, which is still found in some genera at least, in nearly all the families. A new factor having been introduced, viz. the presence of the respiratory entapophyses lying in the large ventral sinus containing venous blood requiring aeration, we accordingly find the second respiratory segment again taking a prominent part in the respiration in many forms, owing to the increase in size and the branching of the medial trunks, accompanied ultimately by a corresponding reduction in the size of the anterior lung-books, e. g. in the Attidæ. This method of origin of the tracheæ is independent of that of the Dysderidse and its allies, and the tracheal tubules, when present, would here not be derived from saccules, but be new formations.
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