492 Mr. E. E. Prince on the Nest and 



observed, this tenacity is increased by the fluid secreted by 

 the ovary, which slowly hardens when exposed to sea- water, 

 and the ova are bound strongly in irregular masses. They 

 cannot be separated save by exerting some force, and distinct 

 facets or scars upon the capsule mark the points of attach- 

 ment to neighbouring ova. Small spaces are left between 

 adjacent ova, and the mass thus possesses a porous or spongy 

 character, a feature of great consequence, to which attention 

 was first drawn by Prof. M'fntosh in the June part of this 

 journal. In describing the ova of Gottus hubalis Dr. 

 Mcintosh said, "All adhered firmly together, yet leaving a 

 series of cavities, so that the whole mass, as in Cyclopterus^ 

 imbibes and retains water, a provision of importance in 

 the case of eggs deposited near low- water mark " *. 

 When newly extruded the ova exhibit a delicate pale- 

 green hue, which, however, soon gives place to the 

 characteristic translucent amber tint. The capsule is hya- 

 line, very dense, and resistent, the thickness being '0013 

 inch, and it is separable into lamellae. In microscopic section 

 from twenty-five to thirty strata can be distinguished, and upon 

 roughly tearing the capsule the successive lamellse are 

 readily seen (PI. XIY. fig. 2). The capsule is minutely 

 punctured, the pits being arranged in parallel rows (PL XIV. 

 fig. 2). The micropyle is very distinct, and exhibits the 

 usual funnel-like form, bold strise radiating from the external 

 aperture and giving it a stellate outline when viewed from 

 above. A large mass of pale yellow oil-globules are aggre- 

 gated at the vegetative pole and maintain usually a position 

 in the segment opposite the germinal pole. About two 

 hours after fertilization the protoplasmic cap is formed, and 

 cleavage proceeds in the usual manner, the 16-cell stage being 

 completed about the twelfth hour. The morula is reached at 

 the thirtieth hour, and the periblast is then boldly marked, 

 though no nuclei are apparent. In cross section the usual 

 triangular form of the periblast is seen. The disk occupies 

 the under side of the deutoplasmic globe j but if the ovum be 

 shifted so that the disk becomes uppermost, it occasionally 

 remains in that position, or, as is usual, regains its normal 

 position slowly, and apparently with difiiculty, the oil- 

 globules having little power to " right " the disk. Delicate 

 filaments, often very numerous, connect the mass of globules 

 with the under surface of the disk. Similar pseudopodial 

 threads were noted in Tinea by E. van Beueden, and in 

 Gastrosteus acideatus and G. pungitius by Ransom, 



* Ann. & Mag. Nat. Hist, June 1886, p. 433. 



