414 MONOGRAPH OF THE AUSTRALIAN MAUSIPOBIIASCHII, 



Takinr' into consideration the small size and imperfect develop- 

 ment of the specimen, I do not consider that these characters 

 •can be held to equal in importance the tenuity of the body and 

 the presence of the lateral line. 



Castelnau's reason for rejecting this ammocoete as the larval 

 form of a Geotria seems to be mainly based on the fact that he 

 had previously received " a very young individual, only three 

 inches long, having exactly the same form, the same dimensions, 

 and the same dentition " as the specimen of Geotria australis from 

 which his description and measui'ements of the adult were drawn 

 up, and which I shall show further on to have been in truth a 

 Velasia stenostomus. His words are : — " I should have thought 

 this might be the first state of Geotria,'*' but we have just seen 

 that I had a still smaller specimen of this which has entirely the 

 form of the adult." 



That the length of the unique example of Yarra sim/ularis 

 was " four and three-eighth inches," or one and a-half times the 

 length of the perfectly formed individual mentioned above, is not 

 sufficient reason for denying its identity with the ammocoste of 

 Velasia; the difference in size is capable of explanation in at least 

 two ways, tlius : — On the one hand the smaller specimen which, 

 having developed teeth, must have passed the ammoceetal stage, 

 may possibly laave been the young of the true Geotria australis, 

 which, as we shall subsequently show, occurs also on the Victorian 

 coast, while on the other hand the metamorphosis may in this 

 individual case have been retai'ded from some cause, or at all 

 events incomplete. 



Neoynordacia hotvittii. 



In his diagnosis of JVeonwrdacia Castelnau relies for the 

 validity of his genus on the following unstable character : — 



It " has no first dorsal, or rather has only one dorsal, separate 

 and rather distant from the caudal." 



* Lege, Velasia. Castehiaii does not appear to have ever seen a true 

 (ieotria australis. 



