J. MURRAY ON GASTROTRICHA. 217 



contain no single distinctive character, and if it were not for 

 his figures their recognition would be impossible. But he was 

 not a slipshod observer, and when he happens to mention a 

 distinctive feature I have no doubt the animal observed possessed 

 it. Thus when he distinguishes C. maximus from C. larus by 

 its dorsal bristles of equal length, we must give him the credit 

 of supposing that his animal looked like that, unless naturalists 

 agree that no such animal exists a difficult thing to prove. 

 There are species with the dorsal bristles approximately of equal 

 length, and so Gosse is not justified in identifying as C. maximus 

 a species having the posterior bristles much longer. 



In the separation into larger groups, sub-orders, or families, 

 the group has been equally unfortunate. The classification by 

 Fraulein Griinspan (26) recognises three sub-orders : 



Suborder I. Euwhthtdina, having a forked tail. 



II. Pseudopodisa, having an apparently forked tail. 

 III. Apodixa, without a forked tail. 



55 

 55 



I am unable to grasp the distinction between a forked tail and 

 an apparently forked tail, and the Apodina include one genus 

 (Stylochaeta) which has a forked tail ; minute certainly, but is a 

 small tail not a tail ? 



Zelinka's (71) classification is consistent, but the more puzzling 

 genera were not discovered when he wrote. He recognises two 

 sub-orders, and, I should suppose, three families, though he only 

 names two : 



I. Sub-order : Euichthydina, having a "furca." 



1. Family Ichthydidae, without bristles. 

 Genera Ichthydiu'ni and Lepidoderma. 



2. Family Chaetonotidae, with bristles. 

 Genera Chaetonotus and Chaetura, 



II. Sub-order: Apodina, without a "furca." 

 Genera Dasydytes and Gossea. 



Collin (9) follows Zelinka's classification, naming the family 

 Dasydytidae, which includes all the Apodina, and allocating 

 all the genera described since Zelinka's work to places in the 

 three families. 



All this is very unsatisfactory. The anomalies of these systems 

 I have pointed out as exemplified in that of Fraulein Griinspan. 



Journ. Q. M. C., Series II. No. 73. 15 



