DEVELOPMENT AND LIFE-HISTORIES OF TELEOSTEAN FISHES. 861 



cured in April, with the anus about the centre of the body, and a small mass of yolk 

 containing a considerable oil-globule towards the posterior part of the abdominal cavity. 

 It is less elongate than a Clupeoid. The gut passed backward for a distance somewhat 

 longer than that between the snout and the abdominal wall behind the yolk-sac, and 

 terminated about the middle of the marginal fin. A line of black chromatophores ran 

 along the abdominal wall ventrally, and another (subnotochordal) was continued over 

 the gut. The notochord was unicolumnar. In certain structural features this approaches 

 the larval form of Labrax lupus, as shown by Eaffaele * in his valuable paper, but the 

 form of the fish appears to be more slender and elongated. 



Another unknown form (G), procured in March, is characterised by a similar position 

 of the anus (about the middle of the body), and the presence of a large oil-globule towards 

 the posterior part of the abdomen. No trace of yolk has been observed. t It is a slender 

 and elongated larval fish, eel-like in outline, though the precise relationships are unknown. 

 It occurs very regularly in March. The larval eel has not yet been described, and any 

 suggestion on this head is conjectural. 



Cottus. — The youngest post-larval stage of a Cottus, which may be the earlier con- 

 dition of Cottus scorpius, was procured at 4 fathoms in the mid-water net 4 miles off the 

 West Rocks, St Andrews, 28th April 1887. It measured barely 6 mm.; the marginal 

 fin is continuous, though there are indications of a differentiation anteriorly (first dorsal) 

 and ventrally (anal). Two small flattened ridges indicate the ventrals. The pectorals 

 are large fan-shaped organs. A few black pigment-specks occur over the brain, and a 

 large dark band passes from the region of the pectoral to the anus on each side. The 

 preopercular spines are developing. The notochord has a comparatively slight bend 

 upward ; the hypural elements are in process of rapid development inferiorly, the region 

 being distinct from the larval tail, which is still large, so that the organ is bifid. 



The next stage of this species was captured on the 22nd July 1887, in the mid-water 

 net, at 33 fathoms, about five miles off St Abb's Head (W. by S.), in an area of 37 fathoms. 

 The length was 7 5 mm. In this condition the young forms agreed with the older stage 

 in presenting a pair of large tubercles on the nape, while the so-called anterior tubercles 

 were represented only by a spine. Similar elevations occur in other Cotti, and are 

 especially visible in young specimens. The black pigment-bands slanting downward 

 and backward at the side of the abdomen are less marked than in the older form. The 

 tip of the notochord is larger and more prominent than in the latter. 



In life this form had a nearly transparent body, with a series of black spots along the 

 ventral margin from the anus to the tail. The cheeks and under surface of the snout 

 were also dotted with black specks. 



Cottus quadricornis. — Examples (PI. XVII. fig. 11) of a somewhat older post-larval 

 stage than in the preceding form occurred in Crail "Har'st" on 20th July 1887, on 

 ground 15 fathoms deep, with the mid- water net at 13 fathoms, and subsequently in St 



* No. 125a, p. 15, tab. iv. 



t This form is described and figured in the Seventh Annual Report of the Fishery Board for Scotland, 1889. 



