The fauna of the Chazy limestone / by Percy E. Raymond.

  • Raymond, Percy Edward, 1879-1952.
Date:
[1905]
Catalogue details

Licence: In copyright

Credit: The fauna of the Chazy limestone / by Percy E. Raymond. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    P. PJ. Paymo)Hl—of the Chazy Liviedone. 3TJ OrthiiUnm lamellos(( sp, nov. A'entral valve strono-ly convex, the area ln<>’li and curved backward. Delthyrinin narrow and open. Aloiio- tlie middle of the valve is a narrow and shallow depression in which there is one ])lication. The outline of the shell is snlxpiadrate. The o'reatest lenu'th is at the hiiii^e and the cardinal extremities are sliin'litly alate. The dorsal valve has a narrow median sinus, which extends from the beak to the front and nsnally contains 2 ])lications. There are commonly about 20 sharp jilications, which are crossed hv strono; concentric lamellae of i>;rowth. An averai>’e specimen is 8^'“ long and wide. Locality.—Yalconr Island, Chazy, and Crown Point, New York. The types are in the 1 ale LTniversity Miisenm. PELKCYPODA. Ctenodonta per acuta sp. nov. Shell small, longer than high, the beak about one-third the length from the posterior margin. Front rather drawn ont, as in Gtenodoiita nasutxt Hall. The greatest convexity is at the umbo, the posterior slope v^ery gradual. Both slopes to the binge abrupt, but that to the basal margin gentle. One speci- men is 12™™ long and 9™™ high. This species may be distin- gnished from the succeeding one by its more depressed valves and by the prolongation of the anterior margin into a some- what nasute extension. I^ocality.—Found in some numbers in the trilobite layers at Sloop Bay, Yalconr Island, and in the middle of the Crown Point section. The type is in the writer’s collection. Ctenodonta limhata sp. nov. Outline nearly circular, the beak back of the middle. Greatest convexity near the middle of the valve; all slopes steep. The cast shows a few faint lines of growth. Length of largest specimen 10™™; height 10™™. A smaller one measures 8 x 8™™. Locality.—All the specimens are from the trilobite layers. Sloop Bay, Yalconr Island. The types are in the Yale Uni- versity Museum. Ctenodonta duhiaformis sp. nov. Shell small, moderately convex, beak subcentral. Greatest convexity on the umbo, the slope from it to the base nearly flat. Basal margin nearly straight. Anterior end nasute and