308 y^r. A. H. Claik on the Genus Encrinus. 



Mandible. 



Total length 137 



T>enofth of symphysial region 58 



Width at hinder end of symphysis 14 



„ at narrowest point behind anterior expansion 6*2 



EXPLANATION OF THE PLATES. 



PLiTE VIIL 



Fig. 1. Steneosaurus leedsi, sp, u. Semi-diagrammatic figure of the upper 

 surface of the type skull (li. 3320). i nat. size. 



Fig. 2. Steneosaurus durobrivensis, sp. n. Semi-diagrammatic figure of the 

 upper sui'face of the type skull (Leeds Coll. 18). ] nat. size. 



Plate IX. 



Fig. 1. Steneosaurtis nasutus, sp. n. Upper surface of type skuU 



(I!. 3.577). 1 nat. size. 

 Fig. 2. Steneosaurus obtusidens, sp. n. Semi-diagrammatic figure of the 



upper surface of the type skull (R. 31Gd). \ nat. size. 



XXXIX.— TAe Genus Encrinus. By Austin Hobart 

 Clark, of the United States Bureau of Fisheries. 



Mr. F. a. Bather in 1898 (' Natural Science,' xii. p. 245) 

 attempted to unravel the snarl in which the generic names of 

 the recent (and fossil) Pentacrinitidse have become enmeshed, 

 thanks to tlie nomenclatorial carelessness of certain of the 

 writers on the subject of the Crinoidea. Passing over the 

 fact that Balanocrinus is not available for any genus of 

 Pentacrinitidae, that Metacrinus was first diagnosed in 1882 

 (Bull. Mus. Comp. Zooh x. p. 167), and that Isocrinus was 

 first proposed in 1836 (L. Agassiz, M^m. de Soc. de Sci. Nat. 

 de Neucli^tel, i. p. 195, type Isocrinites penduluSj de (sic) 

 Meyer, 1835, nomen \\M^w.m, = Isocrinus pendulus, von Meyer, 

 1837), we come to a consideration of the genus Encrinus. 

 Mr. ]3ather ascribes Encririus to Schulze, 1760 ; but Schulze 

 was not binomial, as a glance at his work suffices to show ; 

 moreover, if he were, why does not Mr. Bather use liis genera 

 Decacnimos., PolyactimSj and Trisccedecacnimos instead of the 

 later Antedon and Actinometra? 



