﻿24 SMITHSONIAN MISCELLANEOUS COLLECTIONS [VOL. 47 



zooecial tubes. The difference is regarded as fundamental, and 

 doubtless separates the two families farther than was believed for- 

 merly. 



It is a curious fact that in all essential respects the structures of 

 the walls of Hcterotrypidtc, as compared in tangential sections, is 

 practically the same as in the cryptostomatous genus Escharopora. 

 At present we see nothing indicating close relationship in this resem- 

 blance, but the fact that it is so should not be overlooked by those who 

 have yet to be convinced of the bryozoan nature of the Trepostomata. 



For purposes of convenience in classification, the Heterotrypidce 

 may be divided into two sections or subfamilies, the first, including 

 Hctcrotrypa, Dckayella, and Cyphotrypa new genus, having numer- 

 ous diaphragms, and the second, including Dckayia, Petigopora, 

 Leptotrypa, Stigmatella new genus, and Atactopora, with dia- 

 phragms few or wanting. 



Synopsis of generic characters 



A. Diaphragms numerous : 



i. Hctcrotrypa Nicholson: — Zoarium erect, frondescent; acantho- 

 pores of one kind ; small ; mesopores varying in number, gen- 

 erally abundant, sometimes wanting almost entirely. 



2. Dckayella Ulrich : — Zoarium erect, ramose or frondescent ; two 



sets of acanthopores, large and small ; mesopores variable, gen- 

 erally more or less numerous. 



3. Cyphotrypa new genus : — Zoarium massive or laminar, never 



erect ; acanthopores of one kind ; mesopores wanting. 



B. Diaphragms few or wanting: 



1. Dckayia Edwards and Haime :— Zoarium erect, irregularly ra- 



mose ; acanthopores of one kind, generally of large size ; meso- 

 pores very few, generally wanting. 



2. Petigopora Ulrich: — Zoarium forming small, circumscribed 



patches ; acanthopores well developed, of one kind ; mesopores 

 wanting. 



3. Leptotrypa Ulrich: — Zoarium forming thin, evenly spread, par- 



asitic expansions; acanthopores very small, never abundant; no 

 mesopores. 



4. Atactopora Ulrich: — Zoarium as in Leptotrypa; true mesopores 



wanting; surface studded with subsolid elevated spots; acan- 

 thopores small, very numerous, inflecting the walls. 



5. Stigmatella new genus: — Zoarium incrusting, massive or sub- 



ramose; mesopores present, often restricted to small spots; 

 acanthopores small, more or less abundantly developed at 



