Fishes — Insects. 6381 



the varieties of colour just alluded to, and my conjecture is that for some of the modi- 

 fications the provision may consist in the proportion and distribution of the minute 

 veins. For example, retardation of the circulation and detension of the blood in the 

 veins seems to favour the production of black, as in the case of the black pigment of 

 the choroid coat of the eye and the co-existence of the vence vorticosce of that structure. 

 This capillary arrangement may be such as to produce a pattern, and this inscribed on 

 the egg before its expulsion would give it the peculiarities belonging to its particular 

 species. The case may not be quite so simple as here supposed. Besides the capillary 

 vessels, the follicles and the epithetial element of the mucous membrane of the duck 

 are very probably concerned in producing some of the phenomena. The deposit of 

 earthy matter, forming the shell of the egg, may itself be brought about by something 

 like the conditions which determine the deposit of bony or earthy matter beneath the 

 attached surface of serous membranes. I shall be greatly obliged if some of the readers 

 of the ' Zoologist,' who may be skilled in making fine injections and microscopic 

 researches, would take advantage of the coming spring to make some of the inquiries 

 here suggested. — Thomas Hodgkin ; 35, Bedford Square, January 24, 1859. 



A Word on Otolithes. — It may perhaps interest your ichthyological correspondents 

 to hear the results of my examination of the otolithes or ear-bones of fish. I have 

 examined upwards of one hundred species, and can now positively slate that they 

 possess generic characters, and I believe I can as positively state specific ones 

 also. Such is unquestionably the case with the Gadoids; of course the specific cha- 

 racters are less marked than the generic, but with care can be made out. I have also 

 discovered that the Gadoids were in great numbers during the deposition of the crag, 

 having obtained otolithes of cod, whiting, whiting pout, pollack, &c, and, from the 

 Lower Marine of Hampshire, the whiting pout and some closely-allied species. The 

 greater part of my series is at present in the hands of Professor Agassiz, to whom they 

 were forwarded after my return from the States last autumn : as soon as I again 

 receive them, I shall be most happy to show them to any of your correspondents who 

 may feel an interest in the subject. As I purpose still continuing my investigations, 

 I will inform you of any further results. — Edmund Thomas Higgins ; 2, Tamworth 

 Place, Red/and Road, Bristol, January 17, 1859. 



Food-plant of Lycana Agestis. — When I took the ' Zoologist' in hand, and saw 

 Mr. Morris's paper (Zool.6336), I expected he had been so fortunate as to have found 

 the larva of Lyca3iia Agestis feeding on the Heliauthemum ; but I find, on reading it, 

 that he has only confirmed my experience that it is the Erodium, and the Erodium 

 only, on which the larva feeds. Mr. Morris says,"L. Agestis is often found very 

 abundantly on the downs in this neighbourhood, where the Helianthemum is also 

 plentiful." I hope Mr. Morris will make himself better acquainted with the Botany 

 of Surrey. Again, he says, " I have also taken L. Agestis at different times in 

 localities so far from the chalk or sand that I am certain there was neither Erodium 

 nor Helianthemum within miles:" here, again, what he shows is simply want of 



