1184 THE VOYAGE OF H.M.S. CHALLENGER. 



Genus Platophium. Dana, 1852. 



1852. Platophium, Dana, Amer. Jouni. Sci. and Arts, ser. 2, vol. xiv. 



1852. „ Dana, U.S. Explor. Exped., vol. xiii. pt. ii. pp. 831, 837, 1441. 



1857. Cyrtophium, Spence Bate, Synopsis, Ann. and Mag. Nat. Hist., ser. 2, vol. xix. (sep. copy, p. 17). 



1862. „ (pars), Spence Bate, Brit. Mus. Catal. Ampli. Crust., p. 273. 



1862. ,, Bate and Westwood, Brit. Sess. Crust., vol. i. p. 479. 



1878. „ Spence Bate, Crustacea in Couch's Cornish Fauna revised and added to, p. 59. 



1880. „ (pars), Haswell, Proc. Linn. Soc. N.S.W., vol. iv. p. 342. 



1880. ,, Nebeski, Beitrage zur Kenntniss der Amph. der Adria, p. 46. 



1882. ,, (pars), Haswell, Catal. Australian Crust., p. 271. 



1885. ,, Carus, Prodronius Fauna? Mediterranean, pars ii. p. 390. 



1885. Dexiocerella, Haswell, Proc. Linn. Soc. N.S.W., vol. x. pt. i. (extr., pp. 13, 15, 16, 17). 



1886. Cyrtophium, Gerstaecker, Bronn's Klassen und Ordnungen, Bd. v. Abth. ii. p. 494. 



For the original definition of the genus, see Note on Dana, 1852 (p. 257). For 

 Dexiocerella, see Note on Haswell, 1885 (p. 566). Spence Bate united Platophium and 

 Cyrtophium under the latter name, and Mr. Haswell re-divided the genus into Dexio- 

 cerella and Cyrtophium, giving the former name to species which will properly fall under 

 Dana's Platophium, Carus in defining the " Tribus, Crevettina," gives as a character, 

 " pedum abdorninaliuni paria tria (stili caudales) bene formati, ssepe elongati." He places 

 immediately after this the following definition of "1. Fam. Dulichiid^e Cls. Corpus 

 lineare, thorace valde elongato 6-articulato. articulis 2 ultimis connatis, abdomine 5-articu- 

 lato, subtus infiexo, sine stilis caudalibus ; antenna? I. ramo secundario parvo, II. post 

 superiores insertae ; glandulse pedum III. et IV. nulke." Of this family he makes Dana's 

 Cyrtophium the first genus, including in it Dana's Platophium. But after giving to the 

 tribe three pairs of uropods (stili caudales) well developed, and leaving the family without 

 any, he describes the genus as having the last pair rudimentary, and for the species 

 Cyrtophium danvinii, Spence Bate, he makes mention of three pairs (" uropoda 

 penultima prsecedentibus multo breviora, ramis inaequalibus, ultima rudimentaria"). 

 Some words have perhaps been omitted from the definition of the family, the presence 

 of which would have cleared up the confusion, but it is important to observe that two 

 other statements in that definition exclude both Platophium and Cyrtophium of Dana, 

 for in both those genera the perseon has seven distinct segments and the pleon its full 

 number of six. 



Gerstaecker thus defines the family " Dulichicke, Dana ; " — "Both pairs of antennae 

 with strongly elongated peduncle and short flagellum. Head extended, in front 

 obliquely truncate. First segment of the perason shorter than the following, the sixth 

 and seventh generally completely coalesced. First, third, and fourth [pairs of] limbs 

 short, the three hinder pairs elongate and slender ; the two anterior pairs subchelate. 

 The fourth and fifth segments of the pleon coalesced ; of the three pairs of uropods one 

 wanting." In defining " Cyrtophium, Dana {Platophium, Dana) " as the fourth genus of 



