CRUSTACI2A. 
24 ^ 
M. Hesse, ill liis artiele (Ann. des Seienees Nat. t. vi. p. 51) 
numbered the ninth (but which is only the eighth, as labelled 
on the cover of the August number), gives his researches on the 
genera Doropygus and Dyspontius of M. Thorell, as well as the 
descriptions of four new genera of Entomostraca which inhabit 
simple and compound Ascidians. Ha treats first of the genus 
Dor'opygus (Thorell), which he divides into two groups, accord- 
ing to the termination of the plcon, and these again into sub- 
groups. 
I. Pleon terminating in a rounded extremity. Appendages straight, un- 
armed, with or without hairs. 
a. Posterior prolongation of the pereion large. 
Doropygus curculio, Hesse, p. 54. — D. pulex ? (Thorell), Hesse, p. 55. — 
D.propinquuSy sp. n., Hesse, p. 56. — D. conicus, sp. n., Hesse, p. 57, in Cynthia 
microcosmus. — D. callipygus, sp.n., Hesse, p. 58, m Ascidia venosa. — D. dc- 
Jlexus, sp. n., Hesse, p. 58, found under the cortical envelope of a zoophyte 
attached to the legs of Maia sqidnado. — D. ohlonyus, sp. n., Hesse, p. 59, in 
Polyclmium stellatum. — D. roticiidus, sp. n., Hesse, p. GO, in A^scidia aspersa. 
b. Posterior prolongation of the pereion nil. 
Doropygus verrtccosus, sp. n., Hesse, p. Gl, in Ascidia venosa. — D. albidus, 
sp. n., Hesse, p. 61, in Ascidia intestinalis. — D. viridis, sp. n., Hesse, p. 61, in 
Cynthia microcosmus. — D. gibbosus, sp. n., Hesse, p. 62, in Ascidia intestinalis . — 
D. tumefactus, sp. n., Hesse, p. 63, in a brown pustulated Ascidian attached 
to Maia squmado. 
II. Extremity of the pleon terminated by a small cavity. Terminal ap- 
pendages curved and sharp-pointed. 
a. Posterior prolongation of the pereion large. 
Doropygus gibber (Thorell), Hesse, p. 63, in Ascidia canina. 
b. ■ Posterior prolongation of the pereion small. 
Doropygus acuttts, sp. n., Hesse, p. 64, in a yellow Ascidian. — D. rejlexus, 
sp. n., Hesse, p. 65, in Ascidia venosa. 
c. Posterior prolongation of the pereion nil. 
Doropygus macroon, sp. n., Hesse, p. 66, in a green Ascidian. — D. rufesce?i3, 
sp. n., Hesse, p. 67, in a Ducodinus. — D. coccineus, sp. n., Hesse, p. 67, in a 
yellow Ascidian. 
Dyspontius striatus (Thorell), Hesse, p. 69, on a sponge and on Rhodymenia 
palmata. — D. marginatus, sp. n., Hesse, p. 71, at the base of a compound 
Ascidian. 
Gastrodes viridis, gen. et sp. nov., Hesse, p. 73, pi. iv.* fig. B-B 4, in 
Ascidia intestinalis. Length 2 millimetres, and closely resembles Bota^ 
elms. The ccphalon is small and elongated. Basal joint of antenmn robust, 
supporting a cylindrical flagellum consisting of eight articuli. The frontal 
border of tlie cephalon is produced into a largo rostral-lilco plate, which is 
rounded at the apex, and roaches as far as the distal extremity of the basal 
joint of the antennae. The pereion consists of six somites, and gradually 
increases interiorly and posteriorly, so as to form a large cavity in which the 
ova are lodged. The pleon is straight and cylindrical, and consists of five 
* The reference to the plate, page 86, is erroneously given in the mnnoir 
as ' plate ii. instead of iv. 
