680 PROFESSOR W. C. M‘INTOSH AND MR E. E. PRINCE ON 
soft and pliant, and may remain so even after deposition, as we find to be the case, 
notably in the thick capsules of Gastrosteus spinachia and Cottus. These ova, for some 
time after deposition, are soft and yielding, possessing, as Prof. ALLEN THomson (No. 153) 
states, in the fresh-water congener of the former, “so little elasticity that it usually 
retains dimples or impressions made upon it from without.” In this connection it may 
be mentioned that the so-called outer layer in Clupea harengus is slightly facetted (No. 
87, p. 177), this being due, doubtless, to the impress of the follicle-cells before the egg is 
extruded—a suggestion which may also be applied to the similar appearance in the case 
of Perca (No. 111, p. 187). The zona radiata, as its name implies, has a characteristic 
radiate structure in many Teleosteans, The real nature of the striation so visible in section 
has been much disputed, and there is little unanimity of opinion in regard to it. In 
many species this feature has not yet been made out, eg., in a number of familiar 
Gadoids, viz., G. merlangus, G. eglefinus, G. luscus, Molva vulgaris, and some of the 
Pleuronectidee, such as P. jflesus and P. limanda. The capsule in the familiar 
Pleuronectid, Pleuronectes platessa, again, is very distinctly punctured (Pl. I. fig. 20). 
CUNNINGHAM has recently mentioned that the zona radiata of the cod usually described as 
not punctured (vide Ryprr, No. 141, p. 457), exhibits pore-canals, but he does not describe 
them in the ovum of Zrigla gurnardus; yet the latter, so far as our experience goes, 
shows them much more distinctly than those of the cod; indeed, we have not yet 
satisfied ourselves concerning the latter. In the ovum of Trigla one of us has demon- 
strated that the whole surface of the capsule is minutely and faintly dotted (PL. I. fig. 
19). This punctate appearance is especially distinct after the escape of the embryo. 
The capsule of this form in the unimpregnated condition shows numerous wrinkles—the 
yolk occupying a comparatively small area, so that a large perivitelline space exists, 
which, however, diminishes after fertilisation, until the vitelline globe almost fills the 
capsule, which at the same time becomes less distinctly wrinkled. The corrugation of the 
zona radiata is, however, a characteristic feature, and exists in all the egos of this species. 
The zona is firm and elastic to a remarkable degree for a pelagic form, and its unevenness 
causes some obscurity—only a faint line of dots being as a rule visible along the ridge 
which happens to come into focus under the microscope. In one instance the zona 
presented a series of scale-like markings or areolx (Pl. I. fig. 16), probably due to an 
unusual or morbid condition in connection with the follicular epithelium. The normal 
wrinkles (seen best in 7. gurnardus) also occur in the lemon-dab (PI. I. fig. 18); and 
Ryper speaks of these in G. morrhua as fine lines crossing each other at definite angles. 
Such lines, however, are less visible in eggs which are healthy and perfectly mature. 
The typical zona radiata exhibits, as Von Barr discovered in Cyprinoids, fine striations 
perpendicular to the superficies of the yolk, and Cart Voer described at greater length 
the same feature in the Salmonidee (No. 155, p. 7); while Rercnerr noted it in the ova 
of Tinca vulgaris and Leuciscus erythrophthalmus, and Leypic in Gobius fluviatilis. 
Are these striz really canals, or merely fine fibrillations, such as we find in the 
transient zona radiata of the fowl under a high power? In either case a punctured or 
