DEVELOPMENT AND LIFE-HISTORIES OF TELEOSTEAN FISHES. 889 



the length of 1^ inch ; whereas the adult wolf-fish is boldly barred with dark pigment. 

 On the other hand, the young of the salmon, as well as of allied species, are just as 

 prominently barred in their larval state, as they are uniformly tinted in their adult con- 

 dition. We have seen that the young cod is at first boldly speckled, and later is definitely 

 tesselated, whereas in its adult state the tints are more or less uniformly arranged. 



The ling (Molva vulgaris), again, after the ochre-yellow colour of the early embryo — a 

 colour which extends along the enormous pelvic fins of the subsequent stage — becomes, in 

 a more advanced condition, beautifully striped, and still later is barred in a most striking 

 manner, while the adult form is almost as uniformly tinted as the cod. The young green 

 cod (Gadus virens) is, however, uniformly tinted both in its young and adult condition, 

 the larval stage not yet having been described ; and, as far as is known, the haddock and 

 whiting (PI. XVII. fig. 12), after the absorption of the yolk, do not exhibit any divergent 

 feature in regard to colour. On the other hand, the young gurnard (T. gurnardus) shows 

 little that is noteworthy in the pigment of the early stages, but when f inch in length it 

 is characterised by the remarkable crescentic disposition of the pigment on the pectoral 

 fins. The dragonet (Callionymus) is less beautifully tinted in the young stages than in 

 the adult, but it is noteworthy that the ventral surface of the abdomen is blackish in the 

 post-larval stage — white in the adult. 



The rocklings (Motella) are distinguished by their remarkably long ventral fins, the 

 base being white and the tips black. In the Pleuronectidce there is a tendency to 

 transverse rows of blackish spots, as in the turbot (Rhombus maximus), or in an earlier 

 stage to dots along the bases of the marginal fins, both dorsal and ventral. 



The Integument. — Few features of interest are found in the integument of other post- 

 larval forms, as the scales appear to be late in developing, and the various dermal and 

 epidermal strata are not readily distinguished. In some forms, as in Callionymus, ^ inch 

 long, and Cyclopterus, large cellular spaces occur from the snout to the tail — developed 

 probably in the Malpighian stratum of the integument, and by their increase in size they 

 are pushed towards the surface. Their contents are usually clear in stained sections ; but 

 in Cyclopterus they are coloured very deeply by Beale's carmine, and in all cases are 

 probably glandular. In Cottus, § inch, also very large spherical cells of a similar character 

 appear ; and in the post-larval Labrus, T 7 ^ inch in length, they are most numerous over 

 the frontal and epiotic regions. 



Serous Spaces. — In the early larval condition of certain forms considerable serous 

 spaces occur in the dorsal regions of the head and trunk, but they gradually diminish, 

 and lymphatic fluid appears to collect in chambers, often of large capacity, which occur as 

 in the post-larval gurnard when -fa inch in length, between the roof of the mouth and the 

 cranial floor. A blade-like plate of hyaline tissue is developed in the membrane arching 

 over the two supra-oral cavities. Each plate is placed at an angle, and abuts on the 

 posterior median process of the rostrum. Again, in the cod, |^ inch in length, a large 

 lymphatic chamber occurs behind the urinary bladder, and a network of connective 

 tissue occupies the contained space. Around the fore-part of the membranous cranium 



VOL. XXXV. PART III. (NO. 19). 6 X 



