Apertures of Craniate offactory Organs

Abstract

Bjerring. H. C. 1989. Apertures of craniate olfactory organs.-Acra zool.. Smckh. 70: 71-85.The olfactory organs of craniates appear to derive from an anterior pair of erstwhile branchiothyria and their adjacent epidermal, neurogenic placodes. The organ is termed saccus nasalis if its source is the ectobranchial invagination of the branchiothyrium, and the saccus rhinulis if its source is the entobranchial evagination of the branchiothyrium. Nasal sacs occur in gnathostomes and lampreys. and rhinal sacs in hagfish. It is difficult, therefore, to avoid the conclusion that the olfactory organ has evolved more than once. The rhinal sac has only one aperture, the postica, which represents an internal branchiothyric orifice. Partial fusion of the right and the left rhinal sac led to the development of a postica communis. The nasal sac has either one, two or three apertures. Altogether there are nine different aperturae sacci nasalis. viz. the naris, the foris. the tremiscus. the two nariculae, the rimilla, the portula, the opiscus and the janua. The janua represents an external branchiothyric orifice and occurs in lampreys. The naris and the foris arose by subdivision of the orifice from which the janua emanated; they are found in osteolepipods. The naris is also found in urodeles, porolepiforms and some teleosts. The incurrent and excurrent naricules resulted from bipartition of a naris and are present in actinopterygians, coelacanthiforms, brachiopterygians, dipnoans and elasmobranchiomorphs. Of the four remaining openings of the nasal sacs the rimilla results from an inpushing of the epidermis, the portula from an outpocketing of the nasal sac. and the tremiscus from a combination of two such movements, the one inward and the other outward. Rimillae occur in cyprinodonts. anurans, urodeles. caecilians and porolepiforms, portulae in uranoscopids and bathydraconids. and tremisci in urodeles and porolepiforms. The opiscus, finally, is the opening through which the vomeronasal organ communicates with the oral cavity. It occurs in most lizards and snakes and probably also in some mammals. H. C. Bjerring. Depurtineiit of Pu1ueozoolog.y. Swedish Museum of Naturul Hislory. S-104 05 Stockholm. Swedeit

The mitochondrial DNA molecule of the hagfish (myxine glutinosa) and vertebrate phylogeny

“…On the basis of extensive morphological, mainly neuromorphological Janvier 1993, 1994), studies of new fossils, there is now a growing consensus that Myxiniformes is the sister group of the Vertebrata (Janvier 1981(Janvier , 1996Gee 1996). This understanding is consistent with several previously recognized basic differences between Myxiniformes and true vertebrates (Brodal and F~inge 1963;LCvtrup 1977;Janvier 1978;Jarvik 1980;Hardisty 1982;Bjerring 1989) and was actually foreshadowed by Retzius (1893). The position of Myxiniformes as a sister group to Vertebrata is inconsistent with the Cyclostomata hypothesis, originally proposed by Dum6ril (1806), according to which the Cyclostomata (Myxiniformes + Petromyzontiformes) are the monophyletic sister group to the Gnathostomata (jawed vertebrates).…”

Three‐Dimensional Structure of the Nasal Passageway of a Hagfish and its Implications for Olfaction

“…8). Braun (1996) has previously noted that “lampreys and hagfish show hints of a paired olfactory system in their development and in the gross morphology of their olfactory organs and [nasal] ducts” and Bjerring (1989) suggested that “the hagfish olfactory organ is a dual structure.” The hagfish study Braun was referring to, however, described a paired region in the posterior part of the nasal duct of an embryonic specimen of Myxine glutinosa (Janvier, 1974). The features we describe relate to an adult hagfish.…”

Comparative morphology and evolution of the lungless caecilian Atretochoana eiselti (Taylor) (Amphibia: Gymnophiona: Typhlonectidae)

“…Each sheet is presumed to represent the fused flaps of a choanal valve. Closure of the choana means that no connection exists between the external nares and the buccal cavity, and this is a unique condition among tetrapods (for an alternative view of the nomenclature of tetrapod nasal apertures see Bjerring, 1989).…”