458 Mr. E. E. Prince on the 



Trigla gurnardus : diameter "0598 of an inch. — Spherical 

 form almost constant, spheroidal ova being rare ; capsule 

 hyaline and dense ; vitellus exhibits a large, pale salmon- 

 tinted oil-globule. During development several large 

 cells (multinucleate) occur in proximity to the embryo, 

 and stellate nucleated particles of protoplasm soon after 

 closure of the blastopore occur, distributed over the sur- 

 face of the vitellus. 



Gadus ceglefinus : diameter '058 in. — Ellipsoidal form fre- 

 quent ; capsule thin and of great translucency ; no oil- 

 globules. 



Gadus morrhua : diameter "0551 in. — Ellipsoidal form 

 sometimes preponderates ; capsule hyaline, but slightly 

 denser than in the other Gadoids enumerated here. Shows 

 a faint bluish translucency. No oil-globules. 



Gadus merlangus : diameter '0476 in. — Very crystalline in 

 its translucency. During development exhibits (about 

 the seventh day) one or more enucleate structures, 

 elaborately stellate, usually occurring one on each side 

 of the embryo near the mid-mesenteric region ; some- 

 times a third, asymmetrically placed, occurs. They have 

 the form characteristic of a " bone corpuscle." No oil- 

 globules. 



Pleuronectes flesus : diameter '038 in. — Usually spherical, 

 but ellipsoidal form is frequent. Capsule hyaline and 

 exceedingly tenuous. 



Pleuronectes Umanda: diameter "OSS in. — Hensen compares 

 the ova of this species with the preceding (P. flesus) in 

 the following terms *: — " Those of the flounder are 

 small ; but the smallest of all (less than 1 millimetre) are 

 those of Platessa Umanda^ Capsule hyaline and very 

 thin. The whole ovum exhibits a delicate golden-brown 

 tinge, which is characteristic. On the fiftli day after 

 fertilization the vitellus exhibits a remarkable reticula- 

 tion, apparently due to the peculiar disposition of the 

 protoplasmic yolk-cortex. Polyhedral spaces are enclosed 

 by the intersecting ridges, which appear to be merely 

 superficial and therefore unlike the reticulation which 

 penetrates the entire yolk-mass in Elasmobranchs, 

 forming, as Dr. Schultz discovered, a series of radial 

 lines from the "centre to the circumference. Further, 

 according to Balfourf they exist before and after fertili- 

 zation, whereas in P. Umanda no reticulation is visible 

 until long after fertilization. 



* U. S. Fish. Comui. Rep. 1882, p. 428. 



t Journ. Anat, and Phjsiol. vol. xix. pp. 379 and 541. 



