OCR Text |
Show B. Carina terminating in a fork. Terga absent. Basal segment broader than occludent and of 1902.] CRUSTACEA OF THE " SKEAT EXPEDITION." 373 the same length ...................................................... D. cor Auriv. Basal segment narrower than occludent and shorter. Basal at right angles to occludent ............ D. apevta Auriv. Basal at obtuse angle to occludent, then parallel to fork of carina............................... D. cmieata Auriv. Basal segment absent ................................................. I). angulata Auriv. Terga present. Basal segment broader than occludent. Tergum with three teeth ............................... D. alata Auriv. Tergum shaped like a horse's head and ne°k .................................................................... JD. equina, sp. n. Basal segment narrower than occludent. Basal half as long as occludent, or less. Tergum triangular ................................... D. aymonini Lessona. Tergum with carinal edge rounded, scutal edge with 2 lateral teeth....... D. neptuni Macdonald. Basal more than half as long as occludent. Tergum with 2 teeth. Teeth nearly equal .......................... D. sinuata Auriv. Teeth very disproportionate ........ D. trigona Auriv. Tergum hook-shaped, handle broad. Hook large and blunt..................... D. lowei Darwin. Hook small and sharp ................. J). darwinii Filippi. C. Carina terminating in a cup. Scutum in two distinct segments. Basal narrower than occludent, tergum with 5 unequal teeth.......................................................... D. orthogonia Darwin. Basal broader than occludent, tergum with 3 teeth ......................................................................... D. occlusa, sp. n. Scutum with a notch only and indistinctly divided. D. sessilis Hoek. D. Carina absent............................................................................. D. bullata Auriv. 2 8 . D ich e l a s p is occ lu sa, sp. n ov. (Plate XXXV. figs. 6 - 6 c.) Loc. Kelantan; Trengganu. Hob. Mouth-parts of Themes orientalis. The valves in this species are all very closely apposecl, much more than in any other species of the genus. The carina extends between the terga by quite 3 of its own length, is rather strongly curved, and has its anterior end expanded, cup-shaped, and embedded in the peduncle. The scutum consists of two segments, of which the occludent is longer than the basal by barely 1 of its own length, has its tergal margin bluntly rounded, and is united at its rostral end to the basal segment by a narrow bridge of noncalcified tissue ; while the basal is 2| times the breadth of the occludent and separated from it only by a very narrow membranous interspace, and is faintly hollowed on its curved carinal margin close to its tergal angle for the reception of the tip of a strong tooth on the tergum. Between this latter tooth and its occludent angle, the tergum is deeply hollowed where it fits round the end of the occludent segment of the scutum ; the scutal margin thus appears tridentate. The capitulum is rather flattened from side to side; the peduncle differs in appearance in the adult and young forms, being in the former swollen, a little shorter than the capitulum, and brown in colour; and in the latter not swollen, a little longer |