DEVELOPMENT AND LIFE-HISTORIES OF TELEOSTEAN FISHES. 675 



fig. 23). This species seems to spawn from January (or perhaps even from December) 

 to April. 



Cottus scorpius (PL I. fig. 3). — The ova present various shades of red, inclining at 

 times to orange or yellow. Their diameter averages "075 inch, and the large oil-globule 

 ranges from "015 inch in diameter downward. The zona is smooth, except where the facets 

 for attachment to adjacent ova occur. Minute dots are visible under a high power, and 

 these have a more regular linear arrangement, as a rule, than in Cyclopterus. Moreover, 

 larger dots occur at intervals all over the surface, recalling those noted in Cyclopterus 

 taken from the stomach of young cod. In the Eeport to H.M. Trawling Commission,* 

 one of us has alluded to the error of Professor Alexander Agassiz in considering the 

 ova of Cottus pelagic, a fact overlooked by Mr Cunningham^ 



Ammodytes tobianus, L. — G. 0. Sars states that the comparatively large ova of this 

 species are not pelagic, but are laid in loose sand, where they go through their 

 development. Couch, again (No. 44, iii. p. 138), considered that it sheds its ova 

 in this country as it dashes through the sand in December; while Day (No. 51, i. 

 p. 333) found the reproductive organs in both male and female, at St Ives, far 

 advanced in August and September. On the other hand, Thompson states that in 

 Ireland they were nearly ripe at the end of July. The organs, however, were found 

 to be small in November at St Andrews. Early in May some specimens (none more 

 than 6 inches in length) showed ripe spermatozoa, though the testes were comparativelv 

 small ; while in the females the ovaries were not much developed, and contained 

 very minute eggs. These eggs were transparent and granular, with a large germinal 

 vesicle. Some larger eggs, five or six times the diameter of the remainder, showed 

 a coarsely granular yolk, with many small oil-globules, and a very thin external 

 capsule, which is finely reticulated, and provided with minute punctures as in other forms. 

 In the ovary the eggs appear to have a somewhat whorled arrangement. Later, about the 

 beginning of June, the reproductive organs in about twenty examples showed an irregular 

 state of advancement, some having fairly advanced ovaries, while others were rudimen- 

 tary. In those best developed the ova were of a rich orange colour, "reddish yellow," as 

 Sars said, and they were just visible to the naked eye as minute grains -^ of an inch in 

 diameter. The germinal vesicle was still very evident, measuring ^^ inch. Most of 

 the larger ova were of this size, though others were much smaller, the smallest being in 

 fact less than the nucleus of the largest eggs, and their nuclei showed many nucleoli. The 

 zona is distinctly dotted at this stage. The sperms in the male fishes showed a distinct 

 head, but no motion was visible at this time. So far as could be observed at St Andrews, 

 the spawning period of this species would seem to be late, indeed so late as to bring it 

 within a reasonable distance of the pelagic larval forms described in a subsequent 

 chapter.}: In some examples, however, examined in the middle of December, the genital 



* 1884. t Op. cit., p. 103. 



t Section xi. Investigations, at present being carried out by Mr W. L. Calderwood at the St Andrews Labora- 

 tory, may clear up the subject. 



