220 
CRUSTACEA. 
PELTOQASTEIDiE. 
Giard confirms the hermaphroditism of the Sicctoria, and gives notes 
on their larvae. C. R. Ixxvii. (1873) pp. 945-948. 
The presence of Sacculina makes crabs sterile ; it is itself destroyed 
through pressure by Molgula socialis, when fixed on the same crab ; 
several other animals, Polyzoa, Annelides^ and Sponges, are to be found 
on the tail of the crab at the same spot. Giard, 0. R. Ixxix. pp. 241-243, 
and Ann. N. H. (4) xiv. pp. 386-388. 
PacJiyhdella carcini (Thomps.). Its Nauplius-stage described by A. 
Stuxberg, OEfv. Ak. Forh. 1873, part 9 (issued 1874). 
ARANEIFOEMIA.* 
Pycnogonida. 
C. Semper has published an interesting paper on the Pycnogonidce and 
their larvae which live parasitically on Hydroid polyps. Arb. Inst. 
Wiirzb. i. pt. 4, pp. 264-286, pis. xvi. & xviii. = Verb. Ges. Wurzb. (2) 
vii. pp. 257-279, pis. iv. & v. In Phoxichilidium mutilatum (Leuck.), 
observed by him in Heligoland, the first stage of development goes on 
within the eggs in the ovisac, and the following stages are found as parasites 
in the intestinal cavity of Hydractinia echinata. At first, the animal has 
three pairs of feet, the foremost armed with claws, the two others with 
long bristles ; when it leaves the Hydractinia^ it has also three pairs of 
definitive feet, but not the same, the first definitive being the third, and 
the rudimentary palpus of the adult animal the second, foot of the 
larva ; in the second moult of the free animal, the fourth pair of feet 
make their appearance. Semper pronounces himself in favour of the 
view that the Pycnogonidce belong to the Arachnida, their cephalothorax 
consisting typically of six segments (not seven, as Dohrn surmised, 
reckoning a segment and pair for the ovisacs), and gives a systematical 
list of all known species. The so-called Phoxichilidium^ the develop- 
ment of which has been described by A. Dohrn, Jen. Z. Nat. v. 1869, is 
probably a Pallene ; p. 258, foot-note. 
Oomerus, g. n. ; distinguished from all other Pycnogonidce by the eggs 
being borne in the femoral joints of the well-developed thoracic feet, in- 
stead of in ovisacs, and by its lateral tracheal openings. 0 . stigmato- 
phorus, sp. n., Hesse, Ann. Sci. Nat. (5) xx. art. 17, pp. 1-17, pi. viii. 
Brest. 
Notes on the larvae of Phoxichilidium femoratum (Rathke) and Nym- 
phon grossipes (F.) ; id. 1. c. p. 7, pi. viii. figs. 13-17, 18-21. 
Nymphon grossipes (F.), mixtum [-<ws] (Kroy.), and hirtum \^tus~\ (F.), 
from the east coast of Greenland ; notes by Buchholz, Zweite deutsche 
Nordpolarfahrt, ii. pp. 396 & 397. 
* The Eooordor considers 'these bettor placed in the Arachnida. 
