DEVELOPMENT AND LIFE-HISTORIES OE TELEOSTEAN FISHES. 827 



cod are shorter than those of the whiting, the tips of the latter leaving a considerable 

 interval between them and the anus. This abbreviation of the abdomen coincides with 

 the very long first anal fin, and is as characteristic of the adult as the young. The snout 

 of the whiting is shorter and broader than that of the cod, and its depth is greater. The 

 long barbel of the cod contrasts with the short process in the whiting. 



At 54 mm. the pigment has increased, and the elongate tips of the ventrals pass 

 beyond the anus. The barbel is distinct but small. It is interesting that no young 

 whiting of this and previous stages has been seen without a barbel, yet Mr Day and 

 other authors do not allude to the subject, apparently considering that the young agree 

 with the adult forms in this respect. Young whiting, between 3 and 4 inches in length, 

 have more than once been observed with a distinct barbel, indeed, a stronger statement 

 may safely be made, viz., that at 3^ inches some present the barbel, others do not. 



The Ling (Molva vulgaris, Flem.). — The ova of the ling measure - 066 to "0916 in., 

 or about 1*08 mm., the oil-globule being T 4 5 of that size. They were fertilised at sea 

 on the 27th April,* at 12 noon. When received at the laboratory at the forty-eighth 

 hour, they were in the biconvex morula-stage. They appear to be more delicate than 

 the ova of the cod and haddock, and many were collapsed, the contracted globe of 

 yolk carrying the oil-globule in its wall of protoplasm away from the inner surface 

 of the zona radiata. The nuclei of the periblast were about one-third the diameter 

 of the blastodermic cells. The zona is not so soft and tough as in the cod and 

 haddock, but shows greater resistance, bursting rather than collapsing under pressure. 



Third Day. — About a fourth of the yolk is covered by the blastoderm, and the 

 rim is broad and distinct. On the following day three-fourths of the yolk are en- 

 veloped, and the shield is outlined ; some show metameric segmentation in the middle 

 region of the trunk. In the median line of the body are a number of clear protoplasmic 

 vesicles between the embryo and the yolk-surface. In many, the blastopore is closing, 

 the optic vesicles are contracted off, and the notochord ends abruptly in the pectoral 

 region, but terminates indefinitely at the caudal end ; fifteen or sixteen somites can be 

 observed, but the three regions of the brain can barely be discerned. The envelope of 

 the yolk (blastoderm) is dotted with pale neutral-tinted corpuscles of various angular 

 shapes which send out processes. The blastoderm shows a double contour (probably 

 epiblast and hypoblast) as it passes off on each side of the embryo. 



On the sixth day the lenses are in process of formation, but cannot be fully made 

 out. The neurula is well defined in the cranial region and has a marked keel. The 

 large cells of the closed rim of the blastopore persist at the posterior end of the fissure 

 between the embryo and the yolk. In other Gadoids, these have generally disappeared 

 at this stage. The blastodermic shield is reduced to a mere film on each side, but the 

 peculiar fan-like mass of cells and protoplasmic threads in front of the pectoral region 

 (as in other species) has larger and more definite cells than usual. The clear 

 corpuscles of a neutral tint scattered over the yolk near the oil-globule are still present. 



* The ling is said to spawn on the Skagerrack in May. 



