BIGELOW: EXPLORATIONS OF THE COAST WATERS. .263 



stage, of about .17 mm. No pigment is yet present. At 50 hours 

 the character of the oil-globule is much the same, but the embryo is 

 now of considerable size, and the pigment has appeared. One of the 

 most characteristic features of this species is the presence of black 

 chromatophores scattered o\er the yolk, present there even at this 

 early stage. At about 74 hours, not only embryo and yolk, but oil- 

 globule as well, is pigmented. At 98 hours, the oldest stage examined, 

 the embryo is far advanced, its length almost equal to the diameter of 

 the yolk. The embryonic pigment consists of few large chromato- 

 phores and similar ones are scattered over both oil and yolk. Even 

 at this stage, there are usually, but not always, several tiny globules 

 close to the chief one. 



This species is easily distinguished, in late stages, from most other 

 pelagic eggs so far identified from the Gulf of Maine, by small size, 

 (.7-.75 mm.) in connection with the structure of the oil-globule, and 

 particularly the pigmented \olk. But it may prove difficult to sepa- 

 rate it from the Rockling {Enchclyopus cimhrius) which has an egg 

 of about the same dimensions, and in which, likewise, there are several 

 oil-globules, when newly spawned, one chief one of .14-.19 mm., 

 pigmented, with several small ones, (Ehrenbaum, 1905-1909, p. 281, 

 fig. C). However, older Rockling eggs from the North Sea have no 

 pigment on the yolk, hence they could not be confused with Squirrel 

 Hake; and though the j-olk is sometimes pigmented in Rockling eggs 

 in the Baltic, this does not seem to be a characteristic feature, but only 

 an occasional manifestation of \-ery dense pigmentation (Ehrenbaum, 

 1905-1909, p. 281). If the eggs which Agassiz and Whitman (1885) 

 provisionally referred to the rockling, [= Mofclla argcntea], really 

 belong there, the American Rockling, like the Baltic, has a pigmented 

 yolk, hence it would be difficult to distinguish these from the eggs of 

 the Squirrel Hake. But they say that "it is by no means certain 

 that the species has been correctly identified" (Agassiz and Whitman, 

 1885, p. 391). Silver Hake eggs in early stages might also be confused 

 with eggs of the Butter fish, (Poronotus triacanthvs), which are of 

 about the same size and often have two oil-globules when newly 

 spawned. But there is no pigment on the yolk or oil-globule in late 

 stages in eggs of this species. 



Eggs indistinguishable from the 50-90 hour eggs of the Squirrel 

 Hake, described above, first appeared on June 10 in tows off Petit 

 Passage and were taken occasionall\' thereafter until September 

 20th (Stations 10300, 10301, 10303, 10304, 10305, 10317, 10318, 10319, 

 off Wooden Ball Island, August 6; off Libbey Island, August 11); and 



