16 



On the Macrotrachelous Callidinj:. 



By David Brtce. 



{:Read l5th January, 1892.) 



Plate II. 



I propose to put before you this evening a few remarks upon 

 certain Bdelloid Rotifers, which I term the Macrotrachelous 

 Gallidince, and to conclude with brief descriptions of four new 

 species. 



The genus Callidina comprises, as is well known, those 

 Rotifers of the Fhilodinadoe which possess no eyes, and is 

 represented in the great Rotifer text-book by 10 admitted 

 species, while seven others are referred to as doubtful or 

 imperfectly described forms. For three of these last I claim 

 readmission. The Callidina constricta of Dujardin is perhaps 

 not satisfactorily described by the French Naturalist, but Mr. 

 Milne has published a very thorough description of a form 

 which he identifies with it, and he states expressly that 

 Dujardin's figure is a very successful one. Indeed, if the 

 species be not admitted on the original description, it must be 

 on that of Milne, and so, too, must C. musculosa, as both species 

 are of frequent occurrence, and easily identified from the 

 characters given. As to the third form, Callidina tridens, I 

 have not yet succeeded in identifying it, but I am not disposed 

 on that account to consider doubtful a species so fully described 

 by an observer who has given special attention to the genus. 

 One other species of Mr. Milne's, C. reclusa, was described too 

 late to be mentioned in the Supplement. These bring the total 

 up to 14 species, and a fifteenth was recently brought before 

 you by Mr. Parsons. If you further add the four species which 

 I shall presently introduce to you, and still two others which 

 will shortly be described by Mr. Percy Thompson, you will find 

 that the humble and usually overlooked genus Callidina numbers 

 no less than 21 species, of which at least 19 occur in this 

 country. It has thus a certain numerical importance, but I 



