406 A HISTORY OF RECENT CRUSTACEA 
These are in reality ectoparasites, though with an ap- 
pearance of being endoparasites. The sheath or enveloping 
membrane moulded on every detail of their bodies is an 
invagination of the hypodermis of the crab in which the 
Entoniscid lives. 
Entoniscus, Fritz Miller, 1862. Parasitic on Porcel- 
lanide. The female has the marsupium open when adult, 
with deeply cut edges to the component plates, and an 
elongate pleon with five pairs of sabre-shaped pleopods. 
The male is comparatively large, with the first antennee 
elongated, six pairs of trunk-feet reduced to pedicellate 
tubercles, and the last segment of the pleon not slit. 
Entoniscus porcellance, Miiller, 1862, on Porcellana sp. 
Entoniscus Miillerit, Giard and Bonnier, 1886, on Por- 
cellana longicornis (Linn.). 
Entoniscus brasiliensis, Miller, 1871, on Porcellana sp. 
Entoniscus Creplinii, Giard and Bonnier, 1887, on Por- 
cellana (Polyonyx), Creplinii, Miller. Fritz Miiller found 
a couple of the Porcellana in almost every tube of the 
Cheeptopteri at Desterro. Only three times did he find 
the Porcellana solitary, once a female, twice a male. Only 
on these three specimens did he find an Entoniscus. The 
parasite makes the animal sterile, and it is inferred that 
the infested crabs either could not find or retain partners. 
Possibly they did not make the attempt to do either one 
or the other. 
Entidne, Kossmann, 1881. The male has the last 
segment of the pleon terminally bifid. This genus since 
its institution has been much subdivided, and the original 
name limited to Entoniscide parasitic on Oxyrrhyncha. 
Entione acher, Fritz Miller, on Achceus sp. 
Grapsion, Giard and Bonnier, 1886. Parasitic on 
Grapside. The female has the marsupium closed when 
adult, the ascendant lamella of the first pair of marsupial 
plates narrow all along; there are two medio-ventral and 
two latero-dorsal ovarian bosses and four dorsal tubercles ; 
the pleopods lamellar, little recurved. The male has the 
sixth segment of the pleon ending in two recurved hooks. 
