716 T. R. R. STEBBING. 



published in the year 1900, and to the discussion of this group by Professor Sars in 1898. 

 The latter author, while highly commending the services rendered to our knowledge of the 

 Epicaridea by MM. Giard and Bonnier in 1887 and subsequent years, raises a protest against 

 the assumption that the mere statement of the host is sufficient to identify the parasite. He 

 points out that ' one and the same species of Crustacea not seldom is found to be infested 

 by several species of parasites.' So far as at present known the Bopyridae are parasitic only 

 on decapod Malacostraca. It is a little confusing that M. Bonnier should make the Bopyridae 

 one of the families of a section Bopyrinae, when Dr Hansen has already made the Bopyrinae 

 one of the subfamilies of the Bopyridae. 



Tylokepon, n. g. 



Among the various genera closely allied to Kepon, Duvernoy, 1840, Leidya, established 

 by Cornalia and Panceri in 1861, is the only one founded on the male sex, and this is unique 

 in the possession of elongate uropods. Among those dependent on characters of the female, 

 Gigantione, Kossmann, 1881, alone has in that sex biramous uropods. Ergyne, Risso, 1816, 

 the Portunicepon of Giard and Bonnier, agrees with Kepon and is distinguished from the 

 rest by having the branches of the pleopods more nearly equal. Caiicricepon, Giard and 

 Bonnier, 1887, has a medio-dorsal boss on each of the last four peraeon-segments. Trapezi- 

 cepon, Bonnier, 1900, has none of these. Grapsicepon, Giard and Bonnier, 1887, has a medio- 

 dorsal boss on each of the last two peraeon-segments, and herein it agrees with the new 

 genus, which differs from it in that, instead of a simple boss on the sixth peraeon-segment, 

 the boss there is strongly trifid. The head also furnishes a striking character for the new 

 genus, being formed as it were of two short stout cylinders with rounded ends, of which the 

 inner ones look as if they were flattened below where they meet, forming nearly a right angle. 



The name of the genus is formed in allusion to its affinity with Kepon, and to the fact 

 that the parasitic species for which it is instituted was found in the branchial region of 

 Tylocarcinits styx (Herbst) as identified by Mr L. A. Borradaile, through whom I received 

 the specimens. 



Though the generic characters above given may not be thought of very high value, they 

 fall well into line with those of the kindred genera already established, and under existing 

 circumstances a new generic name seemed rather a matter of necessity than of choice. 



12. Tylokepon bonnieri, n. sp. PL LIII. 



?. The appearance of the prominent white head has been already described. The 

 peraeon from its opaque orange colour did not show clearly either the division of the segments 

 or the contour of the lateral bosses, but the triple boss in the middle of the sixth segment 

 was white and stood out clearly. The single median boss on the seventh segment was also 

 white and directed somewhat upwards. When mounted this proved to have its rounded end 

 marked off by a slight constriction. The laminae of the first pleon-segment are very large, 

 strongly tuberculate on the upper surface and edges. The following pairs are successively 

 smaller. 



The first antennae are very small, three-jointed; the second a little larger, five-jointed. 



The ' buccal rostrum ' and the pair of maxillipeds, each member of which is consolidated 

 into a single piece of great breadth at the centre with a narrow incurving apex to represent 

 the terminal joints, differ very slightly fi-om the corresponding parts in Gancricepon (see 



