iqi6."J 



Fauna of the Chilka Lake ; Larval Fish. 



385 



Plate xvii, fig. 7 is the most developed of the specimens which I have seen. It is 

 not yet hatched, but in all likelihood is just ready to be hatched. Of course, 

 hatched specimens leave the colony and lead independent lives and that is why I 

 have not come across them. At this stage the eyes become quite prominent and 

 acquire pigments. The pupil looks yellowish-grey with a brownish spot in the middle, 

 and the bulk of the eye looks brownish-black under the high power of the microscope. 

 The yolk-mass gradually decreases in size. Two streaks of black (in places brownish) 

 resembling stellate chromatophores may be seen lying dorso-laterally, one on either side 

 of the notochord. A big chromatophore lies just in front of the yolk-mass. Embry- 

 onic fin-rays may be seen under the high power in the homocercal (not yet true homo- 

 cercy) caudal fin. The embryonic dorsal fin also becomes well developed. No pigments 

 have been found to occur in the embryonic fins. The pelvic fin has not as yet made 

 its appearance. The pectoral fins are well developed and become fan-shaped. The 

 transparency of the body is lost and every preparation to reach the adult form is 

 more or less begun. 



Petroscirtes bhattacharyae, Chaudhuri. 

 (Plate XVII, figs. 8— 11.) 



1916. Petroscirtes bhattacharyae, Chaudhuri, Rec. Ind. Mus., XII, p. 107. 



This species is believed to be a new one and no description of its larval stages 

 seems to exist. Some specimens were obtained off Balugaon on 6-Ü1-1914, and others 

 near Barkuda I. on 19-XI-1914. The specific gravity of the water (corrected to a 

 standard temperature of 15 °C) was about 1*007 on the former occasion and about 

 i' 006 on the latter, showing a low salinity on both. 



Only three distinct stages are available. The smallest specimen found measured 

 3-25 mm, in length and the largest specimen 15-9 mm. (including the middle caudal fin- 

 rays). The following table gives the measurements in mm. of (1) the smallest, (2) the 

 next higher stage — I shall call it medium for the sake of convenience, and (3) the 

 largest specimens available. 



Stage. 



Total 

 length. 



Depth of 

 body. 



Length of 

 caudal fin. 



Length of 

 pectoral fin 



Length of 

 spine. 



Length of 

 head. 



Length of 

 pelvic fin. 



I. Smallest 



3'25 



•6 



No distinct 

 caudal fin. 



•5 



•3 



•8 



Not yet 

 developed. 



II. Medium 



13-25 



2-25 



i-8 



2-5 



1-25 



2-5 



175 



III. Largest 



15-9 



27 



2"I 



3-25 



1-8 



3 



2-25 



The specimen shown in pi. xvii, fig. 8 measures 3*25 mm. in length (stage I). 

 The muscle segments are fairly well developed and are about 34 in number, out of 

 which about 24 can be distinctly made out, the myocommas of the most anterior 

 and the most posterior segments being rather indistinct. The myotomes have 

 not yet quite acquired the shape of the adult and are slightly wavy in chai acter. 



