TYPHLORHYNOHUS NANUS. 649 



the families Mesostomidoe and Proboscidas, aud there are 

 uo features in the structure of Typhlorhynchus whicli 

 forbid us to refer it to one or other of these families. Which 

 of the two is to be selected depends chiefly ou the importance 

 attached to the proboscis. This in Typhlorhynclius 

 diifers sharply from a typical proboscis, such as is found in 

 Macrorhy uclius or Gyratoi-j but not so greatly from 

 that of P s e u d o r h y n c h u s. In all the genera referred by von 

 Graff [2] to this family, however, the proboscis is retractile 

 to some extent. Further, in none of them do the brain or 

 the testes occupy a position similar to that found in 

 Typhlorhynchus, and in Pseudorhynchns alone is the 

 proboscis invaded by the gut space. 



On the other hand, Byrsophlebs amougst the Meso- 

 stomids is characterised by the presence of two genital 

 apertures, the male in front, the female behind — a character 

 that only occurs in this genus aud in Typhlorhynchus 

 amongst the whole of the Rhabdocoela (.s-. str.), leaving out 

 of account the Prorhynchidas. Further, as I think I have 

 sliown, the female genital apparatus of Typhlorhynchus may 

 be compared in detail with that of Byrsophlebs. 



A bursa seminalis provided with a chitinons appendage 

 very like that of Typhlorhynchus occurs in Hyporhyn- 

 chus amongst the Proboscidte and Proxenetes amongst 

 the Mesostomids. 



The peuial apparatus, whilst differing greatly in detail 

 from any of those figured for these families by von Graff, 

 resembles them in a general way, especially in being 

 provided with a chitinous tube or spout (Chitiurohr — cf. von 

 Graff's figures of Hyporhynchus coronatus and Proxe- 

 netes gracilis). 



It is, on the whole, I think, most convenient to place this 

 new genus amongst the Proboscid^e in the neighbourhood of 

 Pseudorhynchns. It differs sufficiently from other Proboscidge 

 to warrant the creation of a sub-family to receive it. In some 

 respects, e. g. the female organs, it shows an approximation 

 to Byrsophlebs, aud may be regarded as to some extent 



