192 THE SUCKER FAMILY. 



which they also differ in regard to the structure of the capsule. 

 The latter presents a minutely areolar appearance (Plate II, 

 fig. 9), due to slight elevations having a more or less linear 

 disposition, the surface somewhat resembling in miniature that 

 of grained morocco leather. In newly-deposited examples or 

 in ripe eggs in the roe, the external configuration shows an 

 almost regular hexagonal character, the sutures being pale, 

 while the central regions are more opaque, probably from 

 increased thickness. After exposure to water a change occurs, 

 the hexagonal facets becoming less marked, while a series of 

 elevations apparently due to a later modification are visible. 

 In oblique views the capsule shows undulating surface-mark- 

 ings. It is at first soft and pliant, hardening subsequently. It 

 is minutely punctured, and the same dense series of layers can 

 be separated as in the wolf-fish and sea-scorpion. The peri- 

 vitelline space is considerable. In colour the eggs vary from 

 pale-straw or honey-colour to a light pink or flesh-colour, the 

 tint being due to the yolk and its oil-globules. They form little 

 masses which firmly adhere to each other, and to the zoophyte 

 or sea-weed, by a glutinous secretion. 



These eggs are very hardy, and even after exposure on the 

 deck of a boat for some hours are readily hatched in the 

 laboratory. In the same way specimens sent a long distance 

 in a little sea-water or damp sea-weed survived the journey. 



The newly-hatched larvae are active, 4'5 mm. in length, and 

 at once swim freely in the water, thus, irrespective of the 

 pigment, differing much from the elongated and somewhat 

 feeble herring. The cuticle presents a finely reticulate appear- 

 ance on the marginal fin, which everywhere has embryonic rays; 

 and many minute globular vesicles or glands occur on this and 

 the sides of the body. The yolk-sac is studded with stellate 

 black pigment-corpuscles and touches of chrome-yellow, and on 

 each breast-fin is a large spot of yellow with black chromato- 

 phores, followed by a narrow yellowish curved band with 

 similar black pigment. A few chromatophores with remarkably 

 elongated processes form a line along the ventral edge of the 

 muscle-plates, but none are found on the dorsal edge. The eyes 

 have a greenish iridescence like a diamond- beetle's wing. The 



