20C 



Part III. — Fifteenth Annual Report 



jelly-fishes (Cyanea and Rhizostoma). From the 22nd July to the 

 18th August they range from 12 to 36 mm.* He states that 

 ' generally only from three to seven are found under the same 

 'jelly-fish.' If removed from the latter, and thrown into the 

 water near it, they at once endeavour to regain their hiding-place. 

 Like all very small fry, they are at first quite unlike the adult, being 

 short, with a high head of peculiar shape, and with the mouth turned 

 upwards. Until they are 20 mm. long, the greatest depth of the body 

 exceeds the length of the head ; but when they are no more than 



70 mm. long, they have become normal in this respect, the 



greatest depth of the body being from about 84 to 82 per cent, of the 

 length of the head. The plates of the lateral line first appear, though 

 indistinctly, in specimens from 15 to 20 mm. long; afterwards they 

 become more distinct, and the lateral carinse appear. In young speci- 

 mens, 35 mm. in length, these parts of the body have quite the same 

 aspect as in the adult. Shortly after they have attained this size, they 

 apparently leave the jelly-fishes, and live independently, in company with 

 young herrings and sprats. Scads of this kind, from 75 to 100 mm. in 

 length, are fairly common late in autumn. 



By the kindness of Mr H. C. Williamson, a specimen, 33 mm. long, was 

 procured at Naples on the 18th August. It has assumed most of the 

 adult characters, even to the presence of keeled plates on the lateral line 

 posteriorly. On the whole, however, it is a shorter and a deeper fish than 

 the adult, with a larger head and eye. The pigment of the body is much 

 less developed than that of the adult, and the two dorsal and the caudal 

 fins are minutely dusted with black. The second dorsal and the anal 

 almost touch the base of the tail. The bases of the ventrals are behind 

 those of the pectorals, whereas in the adult they are nearly in the same 

 perpendicular, and the abdomen has considerably lengthened. The 

 lateral line shows indications of the hard plates (carinse). This specimen 

 would seem to have been spawned in spring, probably in April or May, 

 and therefore the season is earlier than that mentioned by Day, 

 viz., July. 



3. On the Post-Larval and young stages of the Five-Bearded 

 Rockling (Onos muslela, L.). 



The development of the egg of this species was first studied by the late 

 able worker, Mr George Brook, f in his own tanks at Huddersfield, where 

 he reared the form to the early post-larval stage. It was also one of the 

 earliest species dealt with at St Andrews, and, indeed, has been under 

 observation almost every year since 1884. J The separation of the post- 

 larval stages caught in the various tow-nets, however, has always been 

 a task of difficulty. The following remarks, accordingly, are a contribu- 

 tion to the elucidation of this common species in these early stages. 



In a form, measuring 7*5 mm., from St Andrews Bay, on the 17th 

 June, the marginal fin is still continuous, but has true rays developing at 

 its base, both in the dorsal and in the anal regions. True rays also 

 occur in the caudal, in which the tip of the notochord is slightly bent 

 up. In life, its head was slightly olive, with black pigment ; the abdomen 

 silvery, with reddish-brown. Blackish pigment occurred along the dorsum 

 and the sides, chiefly over the former. The eyes were silvery-bluish. The 

 rays of the moderately elongated ventrals were dull yellowish, and thus 



* ' Scandinavian Fishes,' p. 88. 



t Jour. Linn. Soc, vol. xviii. p. 273, 1885. 



X M'Intosh & Prince's 1 Researches,' p. 832, etc. 



