1919-] '^- Southwell & B. Prashad : Studies of hidian Fishes. 227 



showing certain embryonic characters. We will treat of these 

 stages separately. 



I. Shark-like form (fig. i). — We have two specimens of this 

 stage, one a male and the other a female. Unfortunately in both 

 cases nearly the whole of the yolk-cord and the yolk-sac are miss- 

 ing. 



The embryos have a large number of branchial filaments 

 coming out of the gill-openings ventrally. The eyes are large and 

 project on the sides of the head ; the interorbital distance is much 

 longer proportionately than in the adult. The snout is very 

 small and rounded instead of being pointed as in the adult. The 

 mouth owing to the snout hanging forwards comes to lie in a 

 depression. The spiracles are situated just behind the eyes and 

 have a slightly ovoid outline. The nasal openings have all the 

 valves as in the adult. The branchial region is only slightly in- 

 flated. The pectoral fins are attached laterally by a very small 

 base behind the branchial region, but the anterior edge is already 

 growing forwards to unite with the snout to form the disc. The 

 pelvic fins are very small and so are both the dorsal fins. 

 The claspers in the male specimen are merely flat lobes of skin. 

 The tail-fin is not well developed as yet. 



There is nothing special to note regarding the internal anatomy 

 of this stage ; the various points of interest are dealt with further 

 on in the description of the more advanced specimens. 



Measurements of the male specimen : — 

 Total length 



Maximum breadth of the pectoral fins . . 

 Length of the pectoral fins 

 Distance of the pectoral fins from the 



snout 

 Snout measured from the mouth 

 Interorbital distance 

 Tail 



II. Stage with adult form (figs. 2, 3). — The snout is not at 

 all pointed and is rather acutely rounded ; its length is contained 

 less than six times in the total length ; the distance between the 

 outer angles of the nostrils is a little more than half that between 

 the mouth and the end of the snout. The anterior nasal valve is 

 produced far beyond the internal margin of the nostril but does 

 not reach the valve of the opposite side ; there is a large valve 

 arising from the outer angle which is connected with a similar 

 valve from the posterior margin. The valve from the posterior 

 margin has in addition a small lobe arising from its inner surface 

 and covered by the anterior nasal valve. The back is slightly 

 arched owing to the large and swollen branchial region. The 

 pectoral fins are evenly rounded and do not possess the straight 

 margin so clearly shown in Bonaparte's excellent figures of the 

 adult {op. cit) ; the breadth across the widest part of the pectoral 

 fins is contained a little more than three times in the total length, 



