HARDWICKE'S SCIENCE-GOSSIP. 



201 



NOTES ON ROTIFERS. 



THE GENUS DISTYLA : CLASS ROTIFERA. 



IN 18S6 I contributed to Science-Gossip an 

 Article on the genus Euchlanis, in which I 

 figured and described several of the smaller and less- 

 requently occurring forms of that genus, and pre- 

 dicted that in all probability fresh genera would 

 have to be created for them. In the magnificent 

 monograph of the Rotifera, by Messrs Hudson and 

 Gosse, which subsequently came out, this prediction 

 was verified, and the animals were placed in the 

 new genera Cathypna and Distyla. A careful 

 study, under perhaps exceptionally favourable 

 circumstances of two of the species I then described, 

 has given rise to more than the suspicion that the 

 Rotifera of the latter genus are but the extended 



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Figs. 115. — Cathypna Gossei. 



forms of the genus Cathypna. Indeed, so far as the 

 two species referred to are concerned, I have no 

 doubt whatever — when retracted they are undoubted 

 Cathypnse — when extended, as certainly would 

 they be described as Distylse . If this holds good of 

 the remaining species, it will be evident that Mr. 

 Gosse was in error in admitting the genus created by 

 Eckstein. It may seem a bold thing for a humble 

 and isolated worker like myself to venture to criticise 

 the work of an acknowledged master like Mr. Gosse ; 

 a gentleman— to quote his colleague — " whose great 

 knowledge and experience, his keen powers of 

 observation, his artistic skill, and his rare gift of 

 description are known to all, and have made him 

 facile princeps among the writers on the Rotifera." 

 In this eulogy by his colleague, I heartily concur, as 

 I yield to none in admiration of his many great gifts ; 

 and indeed for years I enjoyed the privilege of his 



friendship, and frequent correspondence. However, 

 if a mistake was made, it is easily accounted for. 

 Much of the work was done under failing powers ; 

 (of eye-sight at least) some species (Diaschiza) were 

 described from dead specimens only, and in one case 

 at least, D. Collinsii) from imperfect drawings. 

 Towards the end of the work, new species accumu- 

 lated so fast, that it was utterly impossible to give 

 them proper attention. When studying one form, 

 another, equally new, frequently came into the field 

 of view, and a hurried, and necessarily imperfect 

 diagnosis taken, and drawing made. As a conse- 

 quence, the characters of the species of several of the 

 less-frequently occurring forms, notably in Proales, 

 Colurus, and others, are not drawn with such pre- 

 cision as to render mistake impossible ; and secondly, 

 his notes on most of the charming Rotifera of the 



Figs. 116. — Cathypna Hudsoni.*, 



sub-order Loricata (Pterodinadre, Brachionadae, &c.) 

 the very aristocracy of Rotatorial life, had, as he put 

 it to me, "to suffer by painful compression," to 

 make room for the numerous unexpected new 

 species. I know that before the concluding part of 

 their great work was in the hands of subscribers, Mr. 

 Gosse had Notes and drawings of over sixty new 

 species, for which no space could be found. Under 

 such circumstances we need not be surprised if slight 

 errors should have crept into a work of such magni- 

 tude ; and it appears to me that microscopists would 

 be doing good service by carefully going over the 

 work as opportunities occur, and checking off the 

 result. This article is a humble contribution to that 

 useful, if somewhat thankless work. The Rotifera of 

 the fam. Cathypnadce, are distinguished by the 

 " body being enclosed in a lorica, open at each end, 

 of two plates ; the dorsal more or less elevated, the 



