374 The American Naturalist. - [April, 
all ectoderm cells, are capable of secreting chitin, and the pit is filled 
by this secretion. To this scheme can all compound eyes of Crustacea 
be reduced; with, of course, the addition of pigment cells, etc. In 
the compound eye of Limulus we have a very ancestral condition. 
The ectodermal pit remains open, and there is no distinction between 
cornea and crystalline cone, while the rhabdomeres exist as extremely 
delicate chitinous rods. ‘‘According to this view the compound eyes 
of Arthropods, either in the sessile or in the stalked forms, are nothing 
more than a collection of ectodermic pits, whose outer open ends face 
toward the sources of light, and whose inner ends are connected with 
the central nervous system by the optic nerve fibres. The cells form- 
ing the walls of the pit arrange themselves into three strata, in most 
cases accompanied by three regional functional differentiations. Gre- 
nacher’s classification of the compound eyes of insects into ‘ acone,’ 
‘ pseudocone,’ and ‘eucone’ types refers to the condition of the cells 
and their products in the middle stratum—the vitrellz. Morpholog- 
ically, then, the compound eye of an Arthropod is strictly single- 
layered, although, as is evident, the present conception is entirely 
different trom the monostichous theory maintained by some recent 
writers.” Mr. Watase further describes the development of the com- 
pound eye of Limulus, and inserts as an appendix some observations 
on the eves of starfishes, which, as he shows, can be reduced to the type 
described among the Arthropods—a pit of ectoderm, the cells of which 
secrete a cuticle upon their free ee 
Tortoises Sold in the Markets of Philadelphia.—The 
taste for ‘‘ stewed terrapin’ and ‘‘ snapper soup’ has become so gen- 
eral in Philadelphia, that the United States are now ransacked for the 
means of supplying it. Within a few years the. species sold were the 
‘* terrapin,’’ aeons palustris ; the ‘* red-belly,’”’ a 
insculptus ; the ‘*slider,”’ rysemys rugosa; and the ‘‘ snapper,” 
Chelydra serpentina. Now large invoices of turtles are sent from 
Mobile, New Orleans, and St. Louis, which include the following 
species: Chrysemys bellii, C. elegans, C. concinna, and C. troostii; 
Malacoclemmys geographica, and M. leseurii; total, exclusive of sea 
turtles, ten T All are abundant in the market except the C. 
bellii. =E. D. Copr 
Zoological News. — Vermes. — Beddard (Proc. Zoél. Socy., 
London, 1889) catalogues the Oligochztes of New Zealand, enumerat- 
ing fourteen species. His conclusions of the relationships of the fauna 
