336 PERCY SLADEN TRUST EXPEDITION 



transverse opening, meeting in the middle line. The molar processes meet deeper in 

 the chamber, just under the opening of the gullet. 



In describing the maxillules and maxillse, account must be taken of the fact 

 that there is no agreement among authorities either as to the names to be applied 

 to the leaf-like processes, usually known as lacinim, which are borne on these limbs, 

 or as to the joints which these processes represent I shall assume the correctness of 

 the following view. The maxillules and maxillee of adult Decapoda can be derived 

 from a type provided with five endites and a distal region which probably represents 

 several further segments. Of these endites, the first stands in the region which 

 represents the precoxal joint, the second proceeds from the i-egion of the coxopodite, 

 the third and fourth from that of the basipodite, and the fifth from that of the 

 ischiopodite. The distal region fo^ms the remainder of the endopodite. The laciniae 

 of the maxillule represent the first and third endites. I shall call them the inner and 

 outer lacinioB. The two cleft lobes usually known as the " lacinise " of the maxilla 

 represent each two endites. I shall call them the first and second lobes. The first 

 represents the endites of the precoxa and coxopodite, the second those of the basi- 

 podite. Boas* and Ooutieret have shown that the endite of the ischiopodite is 

 present in the larva, and in the adult is represented by a slight swelling often found 

 at the base of the endopodite. The lacinise of the first maxilliped represent the 

 coxopodite and basipodite (two fused). 



In the maxillule (e in figs.) the inner lacinia curves towards the outer. It is of varying 

 width, widest in Conchodytes (Plate 57, fig. 26 e) and Pontonia, wide also in Anchistus 

 (Plate 56, fig. 25 e), moderate in Periclimenes (Plate 52, fig. le), narrow in Harpiliopsis 

 (Plate 56, fig. 22 e) and Urocaris (Plate 53, fig. 3e). It bears a varying number of bristles, 

 of which a bunch at the end are stouter than the rest except in Conchodytes. The outer 

 lacinia also varies in width. It has an edge directed towards the middle line of the body 

 and bears along this edge a number of stout spines and usually also some that are more 

 slender. In Anchistus, Pontonia, and Conchod^ytes both lacinise are very hairy. The 

 endopodite is bifid at the tip, the proximal branch, which possibly represents the 

 fifth endite, being curved in a short spiral, the distal branch nearly straight. The latter 

 is reduced to a faint lobe in Harpiliopsis (Plate 56, fig. 22 e), Anchistus {lb. fig. 25 e), 

 Pontonia, and Conchodytes (Plate 57, fig. 26 e). The maxillules stand close against the 

 paragnatha, the laciniae of each opposed to those of the other across the middle line, 

 but not quite meeting them. The inner lacinise are behind the cleft of the meta- 

 stoma, with a low median ridge between them ; the outer stand beside the cleft. 

 The endopodite (endognathite) is directed outwards and appears to give a purchase 

 to the action of the limb by hooking its curved process around the outer edge of 

 the lip, which is provided with a notch to receive it. 



In the maxilla {/ in figs.) the first double lobe has disappeared, and is repre- 

 sented only by a slight swelling of the edge of the limb, on which a faint notch 

 sometimes still indicates its double nature. The second lobe is of a good length, 



* K. Danske Vidensk. Selsk. Skr. (6), Afd. ii. i. pi. 2, -figs. 79, 80 (1880). 

 t Ann. Sci. Nat. Zool. (8), ix. pp. 157—167 (1899). 



