478 CRUSTACEA. 



\vcak. Ilippa eremita L., lives buried in the sea sand, Brazil. Albiincs, 

 sy/irnista Fabr., Mediterranean. 



Fam. Paguridae. Hermit crabs. Abdomen long, usually covered with a soft 

 skin and distorted, with narrow anal fin and rudimentary abdominal feet. 

 The first pair of feet ends with powerful chela; , the two last are reduced. Some 

 of them seek shelter in empty snail shells, to protect their soft-skinned abdo- 

 minal region. Pag urns Bernhardus L., CcenolAta rugosa Edw., Birgus latro 

 Herbst, said to climb palm-trees. 



II. BRACHYURA. 



With pits for the reception of the short internal (anterior) antennae 

 and so-called orbits, i.e., cavities for the reception of the stalked eyes. 

 Abdomen short and reduced, without caudal fin, curved round against 

 the excavated ventral surface of the thorax ; in the male narrow and 

 pointed, with only one, more rarely two pairs of abdominal feet ; in 

 the female broad, with four pairs of abdominal feet. In the female 

 each oviduct dilates to form a bursa copulatrix. The third pair of 

 maxillipeds have broad flat joints and completely cover the anterior 

 mouth parts. The just -hatched Zocea larvae of stout shape, with 

 only two pairs of biramous feet and a dorsal spine ; later they assume 

 the Megalopa form. Many Brachyura live on land. 



Fam. Notopoda. Transitional between the Brachyura and Macrura. The 

 two or four posterior thoracic feet are articulated higher up than the four or three 

 posterior pairs, and shifted on to the back. The first pair of feet has large 

 chelae, the last is often modified to swimming feet. Porcellana platy elides 

 Penn, Dromia vulgar is Edw., Litliodes. Latr. 



Farn. Oxystomata. With rounded cephalo-thorax. The frontal region does 

 not project. The buccal frame is triangular. The male genital openings are on the 

 basal joint of the last pair of thoracic legs. Calappa granulata L., Ilia nucleus 

 Herbst, Mediterranean. 



Fam. Oxyrhyncha. Cephalo-thorax usually triangular, with projecting 

 pointed rostrum. There are nine gills on either side. The male genital 

 opening is on the basal joint of the last pair of thoracic legs. The thoracic 

 ganglia are united into one mass. They do not swim but crawl. In-achvs 

 scorpio Fabr.. Maja squinado Eond.. Pisa armata, Latr., Stenorliynclnis Lam. 



Fam. Cyclometopa. With broad, short cephalo-thorax, rounded anteriorly. 

 Without projecting frontal rostrum. There are nine gills on either side. The 

 male genital opening is on the basal joint of the last pair of thoracic legs. Some 

 of them are good swimmers. Cancer pagurm L., Xawtho rivulosus Eisso, 

 Mediterranean. Carcitvus mamas L., Portunus pubcr L. 



Fam. Catometopa. Quadrilatera. Cephalo-thorax quadrilateral. Frontal 

 region is curved downwards. There are fewer than nine gills. The male 

 genital openings usually lie on the sternum. Some of them live for a long 

 time away from the water. Some live in holes in the earth, as land crabs. 

 Pinnotheres pi*nni L., in the shells of Mytilus. P. vetcrum Bosc., in the shells 

 of Pinna ; known to the ancients, who thought that there was a relation of 

 mutual assistance between the crab and the mollusk. Ocypoda cursor Bel., 



