416 MONOGRAPH OF THE AUSTRALIAN MAJiSIPOBRANCEII, 



(3). " Lingual teeth two in number, straight, strong, and 

 conical." 



Without a re-examination of the specimen it is impossible to 

 say whether there were in fact only two ventribasal cusps, as the 

 third one might have been overlooked, either through careless or 

 defective examination as is the case with the specimen most 

 kindly forwarded to me from the British Museum in which the 

 median cusp is as fully developed as either of the lateral ones; 

 sometimes, however, it is absent as in Mr. Hill's specimen, but in 

 that case the bases of the lateral cusps are widely separated. 



(4). "The distance between the two dorsals and the base of the 

 caudal is a little more than the diameter of the mouth." 



It appears to me that this character in itself indubitably 

 proves the identity of Castelnau's Lamprey with Velasia as will 

 be seen by the following measurements taken from my own 

 specimens : — In my Tasmanian type of Velasia stenostomus the 

 longitudinal (longer) diameter of the closed suctorial disk is 16 

 millimeters and the dorso-caudal interspace - which is, I presume, 

 what Castelnau intends — is 15; in Geotria australis on the con- 

 trar}^ the longitudinal (shorter) diameter of the expanded — and, 

 therefore, further shortened — disk is 27 millimeters and the dorso- 

 caudal interspace only 12, or less than a half. 



(5). " The diameter of the mouth is equal to half the distance 

 from the end of the snout to the anterior edge of the eye." 



This applies much more closely to the small-mouthed Velasia 

 than to the large-mouthed Geotria, in which the disk extends full 

 two-thirds of the preorbital portion of the head. 



(6). The colours are those of Velasia. 



In the table of measurements given by Castelnau we also find 

 corroborative evidence of the correctness of my views, while on the 

 other hand certain of the dimensions given are curiously sub- 

 versive of those views but moi^e in the direction of Mordacia than 

 of Geotria. The following table has been drawn up for comparison, 

 the measurements in columns 1, 3, and 4 being taken from 

 specimens in my collection, while those in column 2 ai'e from 



