324 ■ Zoological Society : — 



other of the Arachnida. A chamber is also shown to exist in it, 

 formed by the separation of the epidermis from the other layers, 

 producing a plano-convex lens, similar in form to the anterior 

 chamber of the higher animals, and analogous to it in function. 

 The stemmata and ocelli, like the facets of the compound eye, have 

 peculiarities in their structure for the correction of spherical and 

 chromatic aberration. 



The author concludes by pointing out the striking homology 

 existing throughout the whole animal world in those parts which 

 "were mentioned at the commencement of the paper as forming the 

 essentials of an eye, and considers that it affords a contradiction to 

 the position of Agassiz, " That every great type is formed on a di- 

 stinct plan, — so peculiar, indeed, that homologies cannot be extended 

 from one type to the other, but are strictly limited to each of them." 

 On the contrary, the eye of an Asterius is formed on the same plan 

 as that of a Planaria and a Dajj/inia, and the eye of the Leech pos- 

 sesses the same parts as that of the Helix, while the similarity of 

 the eye of the Cephalopod tp that of the Vertebrata is obvious to all. 



ZOOLOGICAL SOCIETY. 



Deceml>er 1 1, 18G0.— Dr. J. E. Gray, V.P., in the Chair. 



Description or Two New Species of Entomostracous 

 Crustaceans from India. By W. Baird, M.D., F.L.S. 



Order Phyllopoda. 



1. Streptocephalus dichotomus (male). 



The body of this little Phyllopod is elongate and of a dark brown 

 colour (in spirits). In general form it resembles a good deal the 

 Branchipus torvicornis of Waga, found in the neighbourhood of 

 Warsaw. The peculiar twisted and elongated antenna; (character- 

 istic of the male) are furnished with several filaments, and are divided 

 at the extremity into two forks, one of the divisions of which (the 

 longer) is again bifurcate at the extremity. This larger division of 

 the fork is armed with several teeth on the outer edge. The tail is 

 bifurcate, the divisions being, each of them, densely and strongly 

 ciliated on the inner edges. 



Length of body about three-fourths of an inch ; length of an- 

 tennae about half an inch. 



This curious creature was said to have been found alive in a pail 

 of milk. 



Hab. India. 



Order Cladocera. 



2. Daphnia Nevvportii. 



Carapace-valves oval, terminating posteriorly in a rather long 

 sharp spine directed a little backwards, and furnit^hed on both sides 

 with spines. The surface of the shell is reticulated and hirsute, being 

 roughened all over with short spines. The margins of the carapace 

 are beset with short spines also, the dorsal margin from the extremity 



