IN THE SOUTH-WESTERN DISTRICT. 153 



of the pelagic from the demersal type, they are not necessarily important 

 in this connection. It may be noted, however, that the ova of all the 

 Blennies studied by Guitel have precisely similar filaments for attach- 

 ment, only they are confined to the neighbourhood of the micropyle. 

 It has already been remarked that the early Atherine larva closely 

 resembles that of the Blenny, a form in which the ontogeny is marked 

 by no material change of conformation and by hardly any reduction 

 of the embryonic fin area. It is chiefly by the absence of marked 

 Acanthopterygian characters that the Mugiliformes and Blenniiformcs 

 are placed close together in modern classifications, and the larval 

 resemblances are perhaps evidence of the correctness of their proximity. 



So far as I can see, the points noted above certainly appear to suggest 

 that the Mugilidaj have been evolved from an Atherine-like type, the 

 long-tailed larval phase being suppressed in the ontogeny, while there 

 is a further suggestion that both Atherines and Blennies are derived 

 from a common ancestor resembling the latter in general characters. 



I am, however, far from seeking to imply that all Teleosteans with 

 elongated abdomen are similarly derived. In fact it can hardly be 

 doubted that the Blenny-like form is, in respect to the abbreviation 

 of the abdomen, already far from primitive. This is the conclusion 

 arrived at by Eaffaele, who has discussed in beautifully illustrated 

 detail the migration of the anus in A. hepsetus. He regards as 

 primitive the condition in such fish as the Clupeoids and Salmonoids. 

 The secondary condition is retained throughout life in the Blennies, 

 while a tertiary condition is attained by such an ontogenetic migration 

 as takes place in Atherina. INIy own contention is that Mugil, which 

 Raffaele does not seem to have had an opportunity of studying, belongs 

 also to this tertiary group, an ancestral secondary phase being suppressed 

 in its ontogeny. 



• 



Unidentified larva. 



I am unable to identify a vitelligerous larva found by ]\Ir. E. T. 

 Browne in tow-net material from near the merchant moorings in 

 Plymouth Sound on the 22nd September. I did not see it until after it 

 had been preserved in formol. 



The total length is 2*09 mm., of which the pre-anal part occupies 

 •90 mm. The rectum is separated from the yolk by an interval of 

 '21 mm. The yolk is still fairly large, there is no oil-globule ; and 

 I cannot make out any cortical segments, though such may have been 

 present at an earlier stage. Tlie marginal fins are broad, the dorsal 

 commencing in front of the head. Black chromatophores are present 

 on the head, along the dorsum in a continuous row as far as the middle 



