OCR Text |
Show 1902.] OSTRACODA PROM COCOS KEELING ATOLL, 229 which have occurred in abyssal deposits, such as B. milne-edwardsii and B. crosskeiana. They are all, however, of far more frequent occurrence in shallow-water dredgings. A few of the species have a wide geographical range, as B. milne-edwardsii, B. acanthi-gera, and B. crosskeiana, which are also northern species. Of the 10 species of Cythere two are known from northern areas, namely, C. prava and C. stimpsoni. Another species, C. dictyon, is more often found in deep water, being recorded from fifteen out of twenty-five of the ' Challenger' dredgings at depths of 1000 fathoms and more. The remainder are well known from shallow-water dredgings. The genus Loxoconcha is represented by four species, three of which have a fairly wide range, namely, L. alala, L. honohdiensis, and L. anomala. There are three species of the genus Xestoleberis, two of which have a wide range; one of them, X. depressa, is also common in dredgings off the British coast, from the North Atlantic, and also as a post-Tertiary fossil from Scotland, Ireland, Norway, and Canada. The only species of Cytheropteron recorded here, namely C. Iongicaudatum, was originally described by Dr. G. S. Brady from material dredged in the Fiji group. Description of New Species of Ostracoda. (The specimens were not preserved sufficiently well to enable the organisms to be examined.) CYTHERIDEIS ANDREWSI, sp. now (Text-fig. 27.) Carapace suboval, elongate, somewhat a^rcuate and compressed. Dorsal margin, in side view, rather irregularly curved; ventral margin concave and sinuous. Anterior extremity produced ; Text-fig. 27. b (D Cytherideis andrewsi. a, right valve, lateral view ; b, edge view ; c, end view. X 42 linear. posterior evenly and broadly rounded. Edge view compressed ovate. End view subcircular. Surface of the carapace covered with fine pittings; and the muscle-spots in the median area disposed in rosette-form. Length -57 m m. Cocos Island, lagoon ; very rare. This species differs from C. Icevata G. S. Brady in form and also in the surface-markings on the carapace itself; but it is evidently allied in some respects. |