14 



The external maxillipeds are pediform. The first three pairs of thoracic 

 legs are chelate, the 1st pair being the shortest and the 3rd pair the longest. 

 The last two pairs of legs are monodactylous. Bxopodites are usually present 

 on all, or all but the last thoracic legs, but are sometimes entirely wanting. 



The abdominal appendages are of moderate length, the exopodite being 

 longer than the endopodite, and they may be either foliaceous or slender. In 

 the first pair no endopodite is present, but in the male its place is occupied by 

 a " petasma " or " andricum " which is usually a good deal pleated and is 

 sometimes convoluted. In the second pair the endopodite, in the male, carries 

 at its base a little fleshy scale. 



No podobranchias are present on any of the legs. Pleurobranchiae are 

 present on all, or on all but the last one or two, of the last 7 thoracic 

 somites. 



The genus Peneus may be divided into six subgenera as follows : — 



I. Peneus (restr.) S. I. Smith, Proc. U. S. Nat. Mus., VIII. 1885, p. 170. 

 Kostrum toothed both ventrally and dorsally. A pleurobranch is present on 

 somite XIV. Bpipodites on all the thoracic appendages except the last two. 

 Exopodites present on all, or all but the last, pair of legs. Antennular flagella 

 short. Type P. caramote, Kisso. 



II. Pakapeneds, S. I. Smith, Proc. U. S. Nat. Mus. VIII. 1885, p. 170. 

 Rostrum toothed dorsally only. No pleurobranch on the last thoracic somite 

 (XIV). Epipodites absent from the external maxillipeds as well as from the 

 last two pairs of legs. No exopodites to any of the legs. Antennular flagella 

 short. [ The carapace is sometimes fissured (1) longitudinally, from the orbital 

 to, or nearly to, the posterior margin, and (2) transversely, through the 

 branchiostegite. ] Type P. membranaceus Heller. 



III. Metapeneus, Wood-Mason, Ann. Mag. Nat. Hist., Oct. 1891, p. 271. 

 As Parapeneus, except that all the legs, or all but the last pair, have exopodites. 

 [ The carapace is never fissured, and there may be a filamentous vestige of an 

 anterior arthrobranch on somite XIII. ] Type P. nffinis, Edw. 



IV. Parapeneopsis, Wood-Mason MS. name only. Rostrum toothed 

 dorsally only. No pleurobranchiae on the last two thoracic somites (XIII and 

 XIV). Epipodites absent from the external maxillipeds as well as from the 

 last three pairs of legs. Exopodites present on all the legs. Antennular 

 flagella longish. The carapace is fissured on either side (1) longitudinally, from 

 the orbital to, or nearly to, the posterior mai'gin, and (2) transversely, through 

 the branchiostegite. Type /'. styliferus ? Edw. 



