ON SOME LAEVAL STAGES OF FISHES. 73 



tirely confined to the dorsal region of the peritoneum, where they 

 are closely aggregated in a saddle-shaped area over the region of 

 the stomach and rectum. There are also a few chromatophores in 

 the skin behind the base of the pectoral fin. Professors Mcintosh 

 and Prince* give a figure of a later stage identified by them as 

 belonging to Cottus scorpius ; the latter species is abundant on the 

 Scottish coast, but I have not yet met with it at Plymouth. Their 

 figure shows little detail, and they do not note the fact that the 

 characteristic saddle of black pigment is situated in the peritoneum 

 and not in the skin. In the larva figured by them yellow pigment 

 is present on the head and abdominal region. 



Fig. 6, Plate IV, represents an advanced larval stage identified as 

 belonging to the grey mullet Mugil chelo. The little fish was 

 taken in Mevagissey Harbour and sent to our Laboratory alive by 

 Mr. Matthias Dunn, on May 10th, 1890. I have identified it by 

 the shape of its head and snout, and by comparison with more 

 advanced young of the same species which occur abundantly near 

 Plymouth in summer. It was 10'5 mm. in length. The yolk 

 is entirely absorbed, and the body opaque and pigmented. But 

 the fins still retain their larval membranous character, the forma- 

 tion of the fin-rays having only commenced in the caudal region 

 beneath the upturned extremity of the notochord. The air-bladder, 

 a. b., is conspicuous ; the pectoral fins are large. The pigmentation 

 of the skin is a general yellow ground with numerous black 

 chromatophores scattered over it ; the yellow colour would, of course, 

 also be resolved into chromatophores under a higher magnifying 

 power. 



Eaffaele in his paper in the Mittheilungen of the Zoological 

 Station at Naples, vol. viii, gives figures of the ovum, and the newly- 

 hatched larva of a species of Mugil or mullet. The ovum is pelagic 

 and small, it has a single large oil-globule. There is little that is 

 characteristic in the figure of the newly-hatched larva, except that 

 the yolk is ellipsoidal instead of spherical, and the pigment is 

 yellow and black as in the stage I have above described. 



* Development of Teleostean Fishes, Trans. Roy. Soc, Edinb., vol. xxxv, pt. iii, 1890. 



NEW SERIES. — VOL. II, NO. I. 



