394 Professor W. C. Mcintosh [Feb. 1, 



occasionally happens that in turn the mussel proves a source of incon- 

 venience to them, for, settling on the gill-arches of haddocks, the 

 mussels flourish on a site so suitable for aeration and food that they 

 by-and-by press out the gill-cover and impede respiration, just as the 

 shore-crab (which is also fond of mussels) has its eye-stalks wrenched 

 out by the slow but sure grow^th of the young mussels which have 

 fixed themselves in their sockets. Nemesis thus, by a chance of 

 anchorage, converts a favourite food into a permanent inconvenience. 



Again, in connection with the pelagic food of fishes, it is a well- 

 known fact that adult cod are extremely fond of sea-anemones,* and 

 some of the rarest species may be procured in their stomachs, a feature 

 by no means snrj)rising when we remember that Abbe Dicquemare 

 cooked and ate his sea-anemones with great relish, and wrote in their 

 favour, as also did Mr. Gosse in our own country. Now, the pelagic 

 young fishes, instead of roaming near the bottom in proximity to the 

 anemones fixed on the rocks, and running the risk of being themselves 

 captured for food, find in the inshore waters in summer the larval 

 PeacJiise in great numbers conveniently attached by the mouth to the 

 little hydromedusa3 {Thaumantias hemisphserica, and T. melanojys) which 

 occur in swarms in mid-water. Moreover, the somewhat larger young 

 food-fishes (2-3 inches) show the same liking for the coelenterate group, 

 by browsing on the zoophytes [Ohelia genicidata) which cover the 

 stones and rocks with feathery tufts, yet the zoophytes are not much 

 the worse for this treatment, for they by-and-by shoot afresh, and 

 clothe the area once more with a minute forest. The rapidity with 

 which such zoophytes grow is remarkable, though we must remember 

 that in some cases the old stock naturally dies ofi" after having 

 produced swarms of pelagic young. 



Under this rich food, the young fishes grow apace — head and eyes, 

 mouth and accessory organs, body and fins — all rapidly increase, and 

 the little fish, hatched in the spring, say from March to May, is soon in 

 what is known as the post-larval stage, that is, has lost its yolk-sac, 

 has assumed a more or less uniform tint, and has gill-fringes and 

 teeth. It is about a quarter of an inch long, and is both active and 

 intelligent, the large head and large eyes of the young food-fishes 

 being at this stage specially conspicuous, and in marked contrast with 

 such as Coitus. The marginal fin is quite continuous at a quarter of 

 an inch, and the lancet-like termination of the caudal end of the body 

 is noteworthy. 



About this time the ventral fins of the pelagic fishes first make 

 their appearance, for hitherto they have managed to do without them. 

 Moreover, these fins in some, such as the rockling and ling, undergo 

 remarkable development, forming in the latter (Fig. 7) a pair of great 

 ventral wings consj)iciiously coloured yellow ; yet in the adult (a 



* A favourite bait for cod in some parts (e. g. Aberdeen and St. Andrews), 

 and from the fact, amongst others, that star-fishes do not molest them on the 

 books, no bait is more successful. 



