274 
THE VOYAGE OF H.M.S. CHALLENGER. 
Family IV. Pinnotherida 
Pinnotlieriens, Milne Edwards, Hist. Nat. Crust., vol. ii. p. 28, 1837. 
Carapace usually more or less membranaceous, convex or depressed, with the antero- 
lateral margins entire or but very slightly dentated ; front, orbits, and eye-peduncles very 
small. The post-abdomen of the male usually does not cover the sternum between the 
bases of the fifth ambulatory legs. The buccal cavity is usually arcuated anteriorly. 
The merus (and usually the ischium) of the exterior maxillipedes is well developed, and 
the carpal joint is articulated at the summit or at the antero-internal angle, or more rarely 
at the antero- external angle of the merus. Chelipedes (in the adult males) small, or 
moderately developed ; ambulatory legs slender and usually naked ; dactyli styliform, 
unarmed. 
The species are of small size, and many are found living within the shells of bivalve 
Mollusca, Echini, tubicolous Annelida, &c. 
However characterised, the Pinnotheridse constitute at present a somewhat hetero- 
geneous group, which I think it most convenient to define in the sense originally 
indicated by Milne Edwards in 1834. In his later monograph (1852, 1853) Milne Edwards 
separated Myctiris, Scopimera, and Doto ( Dotilla ) from the Pinnotheridae. By Dana 
(1852) Myctiris is constituted the type of a distinct family and arranged next to the 
Pinnotheridae, but Scopimera and Dotilla are widely separated from Myctiris and placed 
in the Macrophthalmidae. 
The few forms occurring in the collection of H.M.S. Challenger must be arranged in 
three distinct subfamilies, as will be seen in the following synoptical arrangement of the 
genera of this group, wherein I have recharacterised the subdivisions established by 
Milne Edwards, and have added a new subfamily to those previously established, which 
includes a few forms not represented in the Challenger collection. 
Subfamily 1. Pinnotherixal 
Pinnotlierinse, Milne Edwards, Ann. d. Sci. Nat., ser. 3, Zool., vol. xx. p. 216, 1853. 
„ Dana, U.S. Explor. Exped., vol. xiii., Crust. 1, p. 378, 1852. 
Carapace usually convex, subglobose or transverse. Front not rostrated. Ischium 
joint of the exterior maxillipedes usually rudimentary or very short ; dactyli of the 
ambulatory legs very short. The ambulatory legs all well developed. 
Genera : — Pinnotheres, Latreille ; Ostracotheres, Milne Edwards ; Pinnixa, 
White ( = Tubicola, Lockington) ; Xanthasia, White ; Pinnotherelia, Lucas ; 
Fabici, Dana; Pinnaxodes, Heller (?) ; Dissodactylus, Smith (?) ; 1 Mala- 
cosoma, de Man ; Holothuriophilus, Nauck. 
1 This genus is regarded by S. I. Smith as typical of a distinct subfamily. 
