320 [Nov. 



ZOANTHA CuV. 



Z. Danai, pallide purpurascens, tentaculis brevissimis, crassitie iion longio- 

 ribus, disco viridi, extrorsuin purpurascente, ore pavvo purpureo-margiiiato, ten- 

 taculis exteniis ba.'ji pallidis. Diam. disci '25. unc. 



Remarkable for the shortness of the tentacula, which, when fully extended, are 

 scarcely longer than the diameter of their base; they are arranged in two series ; 

 those in the outer series are pale at the base. The disc is radiately rugose, bril- 

 liant green, margined both internally and externally with purple. The root is 

 broad, the animals closely associated, capable of extending 1-25 inches. 



1 have named this species as a feeble tribute of respect to the philosopher, to 

 whom we owe the first rational classification of Zoophyta. 



The Committee on the following paper, by Dr. Leidy, reported in 

 favor of publication. 



On some American fresh-water Polyzoa. 

 By JosEVH Leidy, M. D. 



Since I described several species of fresh-water ciliated polyps in the last 

 number of the Proceedings, we have received the Report of the British Associa. 

 tion for 1850, in which I find a very able and complete report upon "the present 

 state of our knowledge of the fresh-water Polyzoa," by Prof. Allman, M. D. 



Prof. Allman has very correctly appli d the term Polyzoa, of Thompson, to 

 the ciliated polyps, because it had been employed prior to the application to 

 them of the term Hryozoa, of Ehrenberg. 



Prof. A. has also invented some very happy terms, applicable to different 

 parts of the structure of the Polyzoa. Thus for the common dermal system and 

 solid basis of a colony of polypes he uses the word L'cencecium. The external 

 tunic of the latter he calls the Ectocyst, and that lining the tubes the Endocyst, 

 and the disk supporting the teutaculai is named the Lophophore. 



According to the characters given to the genus ('ristatella, Cuv., the species 

 which I described in the last number of the Proceedings as C. magnifica, cannot 

 belong to that genus, as I then suspected; for Cristatella has a ' common flat- 

 tened disk adapted for locomotion," nor can it belong to Lophopus, Dumort, for 

 although this has its base of attachment fixed, yet the ova of the animal have no 

 marginal spines, and it therefore must form a distinct genus between Cristatella 

 and Lophopus, with the following diagnosis : 



PECTINATELLA, Leidy. 



Ccencecium massive, gelatinoid, hyaline, fixed, investing bodies. Orifices 

 arranged in irregular lobate areola; upon the free surface. Lophophore ores- 

 centic. Ova lenticular, with an annulus and marginal spines. 



1. Pectin ATELLA magnifica, Leidy. 



Cristatella magnifica, Leidy. Proc. A. N. S., V. 265. 



Hemark. Found only in shaded situations, always incrusting dead branches 

 of trees. 



