122 Misce lla neons. 



Amongst the forms described were the following new species and 

 variety : — Primitia mundula, Jones, var. cambrica, nov. ; P. humilior, 

 sp. nov. ; P. Morgani, sp. nov. ; P. Ulrichi, sp. nov. ; P. Whitfieldi, 

 sp. nov. ; Entomis rhomboidea, sp. nov. ; IStrepula sigmoidalis, sp. 

 nov.; Beyrichia Jlallii, sp. nov. ; Isochilina lineata, sp. nov. ; /. ? 

 fabacea, sp. nov. ; Leperditia Claypolei, sp. nov. : Xestoleberis 

 Wrightii, sp. nov. 



MISCELLANEOUS. 



On a new Entoniscian (Pinnotherion vermiforme, gen. et sp. nov.) 

 parasitic on the Pinnotheres of Modiola. By MM. A. Giard 

 and J. Bonnier. 



The animal which is the subject of this note is doubly interesting, 

 as belonging to a group of little-known Crustacea and as furnishing 

 a new example of parasitism in the second degree. 



Crabs of the genus Pinnotheres occur commonly at Wimereux in 

 Mytilus edidis, Linn., Modiola modiolus, Linn., and Mactra stul- 

 torum, Linn. ; more rarely in Cardium edule, Linn., and Donax 

 anatinum, Lam. Several specific forms are no doubt confounded 

 under the name of Pinnotheres pisum, Linn. In September last we 

 found in an old Modiola (covered with Serpulce and all perforated 

 by Cliona?) a female Pinnotheres of considerable size (15 mill, wide), 

 but differing from P. veterum, Bosc, which is said sometimes to 

 inhabit the Modioke. This female bore no ova, and the ovigerous 

 feet were slightly atrophied. But our attention was particularly 

 attracted by a violet-grey mass, visible through the transparent 

 dorsal integument, and resembling in aspect an egg-mass of Grap- 

 sion C'arolinii, Giard. A puncture made with a slender-pointed 

 pipette furnished mature embryos of an Entoniscian, and taking all 

 the precautions indispensable in such cases, we were soon able to 

 extract the adult female which contained these embryos in her 

 incubatory cavity. The latter occupied the whole left side of the 

 visceral cavity of the Pinnotheres, from the frontal margin of the 

 carapace, and, contrary to what occurs in other Entoniscians, it was 

 prolonged into the caudal portion of the Crab as far as the third 

 segment of the abdomen. The genital glands of the host were 

 atrophied, the liver much reduced and very pale. The sac 

 enveloping the parasite adhered to the right branchial part and 

 passed, as customary, beneath the intestine. 



This parasite, which we shall call Pinnotherion vermiforme, belongs 

 to a new genus. The characters, in the female sex, are furnished 

 especially by the form of the first incubatory plate and by the 



