272 On the Structure of Polycheles sculptus. 



while in the closely allied Haploops the number apparently 

 varies in the different species. 



The openings of the green glands are arranged very diffe- 

 rently from what they are in any other group of Crustaceans 

 known to me. Willemoes-Suhm says, of Willemoesia lepto- 

 dactyla, that " there is no distinct opening for the so-called 

 green glands ;" but he probably overlooked it from its being 

 in an unusual position : it is, with very little doubt, situated in 

 a similar manner in all the allied species. The proximal seg- 

 ment of the antenna, in our specimen, is loosely articulated 

 with the sternum of the antennal segment, so as to be freely 

 movable upon it. It is very short upon the outside, but ex- 

 pands somewhat on the inner side, which terminates clistally 

 in a thin tubular process arising from the oral side of the seg- 

 ment and directed upward to a level with the dorsal side, so 

 that, in the ordinary position of the appendages, its orifice is 

 closed by contact with the proximal segment of the antennula. 

 This tubular process (a, fig. 2) readily admits a large bristle, 

 which can be pushed through it, round into the cavity of the 

 segment itself. A similar process is apparently shown in one 

 of Bate's figures of PentacJieles enthrix ( l Annals,' vol. ii. 

 pi. xiii. fig. 2, 1878), though I find no reference to it in 

 the accompanying text. Bate subsequently, however, appears 

 to allude to this same process as " the olfactory tubercle of 

 the second or outer antenna?," though I cannot find that he 

 anywhere alludes to Willemoes-Suhm's inability to discover 

 the openings of the green glands. 



The branchiostegites extend forward quite over the sternum 

 of the antennary somite ; and their anterior extremities are 

 applied to the basal segments of the antenna?. The epistome 

 is short, not extending at all in front of the bases of the an- 

 tenna?, is nearly on a level with the dorsal wall of the efferent 

 branchial passages, and on a plane above the bases of the 

 antenna? ; so that the efferent passages terminate in the space 

 between the upturned edges of the squamiform processes of 

 the inner sides of the basal segments of the antennula? and just 

 beneath the short two-spined rostrum. The anterior part of 

 the endostome is on a plane somewhat above the plane of the 

 epistome ; but the space below is filled by the soft and 

 fleshy labrum, which projects considerably below the raised 

 posterior edge of the epistome, and does not differ essen- 

 tially from the labrum in Astacida? or Scyllarida?. The other 

 oral appendages are nearly as figured by Willemoes-Suhm 

 for Willemoesia leptodactyla ; one of the lobes of the first 

 maxillipeds, however, appears to assume a function not before 

 noticed. The inner, or endognathal, lobes of these appendages 



