242 A HISTORY OF RECENT CRUSTACEA 



place of the little crab (carcinion) in companionship with 

 the Pinna. In Australian and other Eastern waters, Pon- 

 tonia meleagrince (Peters) occupies the shell of the pearl 

 oyster, Meleagrina margaritifera, and probably also that of 

 Tridacna squamosa. Professor Th. Barrois found the male 

 and female of Pontonia custos constantly together in large 

 specimens of Pinna rudis at the Azores. 



Typton, Costa, 1844, though much like Pontonia in 

 many points, has the dorsal surface arched and the rostrum 

 laterally compressed, an ocellus on the hind margin of the 

 eye, both flagella of the first antennas undivided, the scale 

 of the second rudimentary, and six or seven pairs of 

 branchiae. Typton spongicola, Costa, is, as its name im- 

 plies, a lodger in sponges ; it is a British as well as a | 

 Mediterranean species. 



Family 4. CaricypJiidce. 



The rostrum is slender and sharp-pointed. The first 

 antennas have two short flagella, the second a long and 

 narrow scale. The first two pairs of trunk-legs are chelate, 

 subequal. Frequently the third segment of the pleon is 

 dorsally elevated and compressed. The telson is long and 

 slender. Here are placed three genera Caricyphus, 'the 

 bowed shrimp ; ' Rhomaleocaris, ' the robust shrimp ; ' Anebo- 

 cdris, ' the immature shrimp,' all instituted by Spence Bate 

 in 1888. and all from immature specimens, the largest of 

 which was three-fifths of an inch in length. The seven 

 species included in these three genera are all from Eastern 

 and Southern waters. Though they will interest the 

 specialist concerned with development, they seem but ill- 

 suited to constitute a separate family. 



Family 5 . A canthephyridce. 



The animal is laterally compressed and dorsally cari- 

 nate. The first antennas have two long flagella; the 

 second a sharp and rigid scale. The mandibles have molar 

 tubercle, cutting edge, and ' palp.' The first two pairs of 

 trunk-legs are slender, subequal. The telson is long, 



