OCCURKING IN THE NEIGHBOURHOOD OF PLYMOUTH. 45 



tlie lierriug, spawns in slioals, we must conclude that these shoals 

 of ripe fish are to be sou^^ht at greater distances from shore than 

 the region a few miles south of the Eddystone where the isolated 

 individuals were taken. This conclusion is supported by the paucity 

 of the pilchard ova taken in the tow-net, and it does not permit very 

 sanguine hopes of the practicability of artificially propagating the 

 pilchard on a large scale. But it must be mentioned that, according 

 to the positive statements of the mackerel fishermen, the number 

 of spawning pilchards taken in their nets was extraordinarily small 

 last season ; that it is not unusual for fifty or more ripe specimens 

 to be taken among a single catch of mackerel. 



Another kind of buoyant Clupeoid ovum occurs near Plymouth. 

 This is shown in fig. 31. It is 1*01 or 1*02 mm. in diameter, and 

 has the small perivitelline space characteristic of the majority of 

 pelagic ova. The yolk has the same segmented structure as that 

 of the pilchard ovum but has no oil-globule. At the stage shown 

 in fig. 31 black chromatophores were conspicuous near the dorsal 

 median line of the embryo. The larva hatched from one of these 

 ova is shown in fig. 32. Its length was 3*07 mm., which is less 

 than that of the pilchard larva and less than that of the larva 

 previously described by Hensen and myself. But as the length of 

 a hatched larva probably varies, I think that in all probability this 

 ovum and larva belong to Clupea sjDrattus, the sprat, which regularly 

 occurs in Plymouth Sound in winter. This kind of ovum was 

 taken in small numbers just outside the Sound, to the east of 

 Penlee Point, on January 28th and 30th, 1888. 



Pelagic Ova taken in the Tow-net. 



Some of these, identified as those of the pilchard, sprat, sole, and 

 dragonet, have already been described, but besides these many other 

 kinds were obtained which could be identified with more or less 

 certainty from the descriptions and figures already published by 

 myself and others of artificially fertilized ova taken directly from the 

 parent fish. Some ova taken near the Rame Head on February 6th, 

 1888, measuring 1"36 in one diameter, 1*44 in another, and having 

 an entirely homogeneous yolk, were probably the ova of Pleiironectes 

 microcephalus , of which some specimens probably begin to spawn in 

 February. 



Pleuronectes platessa (the Plaice). 



An ovum of Pleuronectid type of very large size, obtained 

 January 21st, 1888, eight miles south of the Mewstone, probably 



