Keys to the Orders, Families and Genera of Hepaticae of America North of Mexico

Abstract

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. American Bryological and Lichenological Society is collaborating with JSTOR to digitize, preserve and extend access to The Bryologist.The absence of any ready means of identifying the genera of North American Hepaticae has limited the development of interest in the group. The keys presented here attempt to satisfy this need. These keys fall into two categories (a) synoptic keys to classes, orders, suborders and families and (b) under each order and/or suborder artificial keys to the genera, if more than one genus is included. The first type of key necessarily represents a synthesis of the most "typical" characters of the various groups, arranged in a systematic fashion. By its very nature, a synoptic key cannot take into account isolated exceptions or deviant taxa. However, such a synoptic key has the advantage of giving some idea of the salient characteristics and limits of the various groups. By contrast, artificial keys are rightly concerned only with the practical problem of identification. In the synoptic keys to families I have indicated, in parentheses, the genera included in each family. Therefore, in cases of doubt, a specimen can be run through both the artificial and synoptic keys, using one key as a check on the other. A number of other pertinent points deserve mention in this connection :(1) 1 have indicated, throughout these keys, various "traps" into which the unwary may fall. Similarly, exceptions to the rule are indicated. In SCHUSTER: ANNOTATED KEY TO HEPATICAE 3 in a variety of places. Unfortunately, the extreme polymorphism of several genera (Plagiochila, Nardia) makes it necessary to key them out two or more times. In such cases, after the generic name, I have indicated this fact either by giving, in parentheses, the species keying out at this point, or, if the species are numerous, by stating "in part."(7) Critical features in the keys are occasionally italicized. In the case of couplets utilizing more than a single pair of characters, the initial opposed characters are to be regarded as the most salient. Cytological characters involving study of living material are, in so far as possible, relegated to a secondary position. It should be recognized, however, that in some groups they afford by far the best and most evident features for separating genera.(8) Several plates, at the end of this treatment, illustrate key characters within the difficult Jungermanniales (and, in a few cases, Metzgeriales). These figures are referred to as, for example, (3:10), meaning fig. 3, individual fig. 10.(9) In the Order Jungermanniales, the largest and by far the most difficult group, identification is often complicated by the fact that the plants lack all trace of sex organ...

Marine Macrobenthos of NorthWest India-Reviewing the Known and Unknown

“…Spionidae was one of the common speciose families, in the majority of the studies. Spionidae is known to be one of the most ubiquitous benthic taxa (Fauchald, 1977;Blake, 1996) with cosmopolitan species assemblage (Dix et al, 2004).…”