460 CRUSTACEA. 



Tribe 2. Euispoda. 



Body with seven free thoracic segments and as many pairs of 

 appendages. Abdomen relatively short and broad, with abdominal 

 feet modified to form branchial lamellce. 



Fam. Cymothoidae. With biting and sucking mouth parts, broad abdomen 

 with short segments and shield-like caudal plate. The last maxillipeds in the 

 form of an operculum. They live partly as parasites on fish, and partly as 

 free-living animals. Cymotkoa oestrum Leach., C. cestroides Risso, Mediter- 

 ranean. Anilocra meditcrranea Leach., ^Ega licaritiata Leach., Scrolls 

 paradoxa Fabr. 



Fam. Sphaeromidae. Free-living Isopoda with broad head and short, very 

 convex body, which can often be rolled up in a ball towards the ventral side. 

 Splweroma fossarwn Mont, in the Pontine marshes; nearly allied is the 8. 

 granulatum of the Mediterranean. S. serratum Fabr., Ocean and Mediterranean. 

 It also lives in brackish water. 



Fam. Idoteidae. Free-living Isopoda with elongated body, biting mouth 

 parts, and a long caudal shield formed of several segments fused together. The 

 last pair of abdominal feet is modified to form a wing-shaped operculum for 

 the protection of the preceding branchial feet. Idotea entomon L.. Baltic. 



Fam. Asellidae. Body flattened ; the last pair of abdominal feet (pleopods) 

 are stylif orm (not shaped like an operculum). Jeera albifrons Mont. . British 

 seas. Asellus aquatlcus L., fresh-water form. A. cavaticus Schibdte, in deep 

 springs. Limnoria tcrcbrans Leach. L. lignorum, gnaws wood-work in the 

 sea. 



Fam. Bopyridae. Parasitic in the branchial chamber of prawns ; the body of 

 the female is disc-shaped, unsymmetrical, and without eyes. The males are 

 very small and elongated, with distinctly separated segments and eyes. Bopyrus 

 sqidllarum Batr., on Palcemon squilla. 



Here are allied the Entoniscidoe, which are parasitic in the body cavity of 

 other Crustacea (Clrripedia, Pagv-ridts, and Crabs), Cryptoniseus planarioidea 

 Fr. Mull., parasitic on Sacculina purpurea of a Pagurus, Brazil. Or. pyymcem 

 Rathke, parasitic on Peltogastcr. JSntonigcus Porccllance Fr. Mull., lives 

 between the heart and the intestine of a species of Porccllana in Brazil. 



Fam. Oniscidae. Land Isopods. Only the internal lamellae (endopodites) 

 of the abdominal feet are modified to form delicate branchiae, the exopodites 

 constituting firm opercula. The two anterior abdominal feet are sometimes 

 provided with air chambers. The mandibles are without palps. They live 

 mostly in damp places on land. Ligia occanica L., on stones and rocks on 

 the sea coast. Onlsciis tmirarius Cuv., Porccllio sealer Leach., Armadillo 

 culfjarls Latr., A. officinarum Brdt. 



Order 2. THORACOSTRACA.* 



Malacostraca with compound eyes which are usually placed on 

 movable stalks, with a dorsal shield which connects all or at least 

 the anterior thoracic segments with the head. 



* Besides the larger works of Herbst, M. Edwards, Dana, and the essays of 

 Duvernoy, Audouin and M. Edwards, Joly, Couch, etc. compare Leach, 



