LARVIFORM CRINOIDS 



33 



Genus AMPHIPSALIDOCRINUS 8 J. M. Weller. n. gen. 

 Genotype Amphipsalidocrinus scissurus J. M. Weller. n. sp. 



Wanner has recently described two new genera of crinoids — Cranocrinus 

 and Tenagocrinus — from the Permian deposits of Timor which are composed 

 of an infrabasal disc, five basals, five radials and five orals with a lateral anal 

 opening piercing the cup [17, pp. 41, 48]. Tenagocrinus differs from Crano- 

 crinus in that its radials are shrunken so that they no longer meet laterally 

 and the anal opening has been drawn toward the right from the center of the 

 posterior interradius so that the calyx is no longer symmetrical. In Crano- 

 crinus the oral plates are concave and meet each other along ridges which 

 radiate from the center of the crown. In Tenagocrinus the orals are convex 

 and meet in rounded furrows which apparently served as protective receptacles 

 for the contracted arms. Moreover in this genus the stunted radials no 

 longer bore fields for the attachment of the brachial muscles but in a most 

 peculiar fashion the muscles in these forms were attached to sunken areas 

 near the proximal corners of the orals. 



In our collection there is an interesting little crinoid which appears to 

 be intermediate between Cranocrinus and Tenagocrinus. Although the sutures 

 cannot all be clearly seen, the oral dome resembles that of Cranocrinus 

 whereas the dorsal cup appears to be identical with Tenagocrinus. For the 

 reception of this crinoid the new genus Amphipsalidocrinus is introduced. 

 This genus differs from the typical examples of Cranocrinus in possessing 

 shrunken radials and an anal opening which has been drawn to the right from 

 the center of the posterior interradius and it differs from Tenagocrinus in 

 not being furnished with interoral furrows into which the fields of attach- 

 ment of the brachial muscles have migrated. 



Amphipsalidocrinus scissurus J. M. Weller, n. sp. 

 Plate II, figs. 8a-c 



Fig. 6 



Interpretation of the calyx structures of Amphipsali- 

 docrinus scissurus (compare with PI. II, figs. 

 8a, b). 



Description. — The calyx of the holotype is .63 mm. in height and of 

 slightly greater maximum breadth. It is mushroom shaped, expanding rapidly 

 from a moderately sized stem facet into a large, over-hanging star-shaped 



8 d/j0i, (stretching) around; i^aXi's, dome. 



