150 Expedition to the 



treated with such severity by the Pawnees, that they had 

 often entreated an end might be put to their lives. 



The interpreter returned on the 20th, having accomplished 

 the object of his mission. Soon afterwards, Mr. Dougher- 



cond division of the Crinoidea, or Semiarliculata of Miller. It certainly, 

 however, caDuot be at all referred to Poteriocriaites, the only genus 

 which that author has framed in this division of the family. We refrain 

 from distinguishing it by a name either generic or specific, until other 

 specimens can be obtained, in which the characters are less equivocal. 



We have two second coslat plate?, which made part of distinct individuals, 

 larger than the above described one. Of these the surface of one is per- 

 fectly glabrous, whilst that of the other has light orbicular indentations in- 

 stead of tubercles ; a third very small one is perfectly smooth like the first, 

 and doubtless formed part of the body' of a young individual. 



Another plate found near the same spot with the above, is of a some- 

 what triangular form exteriorly, or rather like the face of a truncated py- 

 ramid, of which the middle of the summit is a little produced in the form 

 of a right angle, thus offering a scollop on each side of the apex for the 

 adaptation of superior ossicular. On divesting it carefully of its extra- 

 neous matrix, we discovered that it was readily adjusted by its base to the 

 summit of those segments of the fragment above described, winch we 

 have supposed 10 be second cstals, a prominent line on its base corres- 

 ponding with the inner one of those grooves which we have described, to 

 characterize the superior face of those plates. This plate then, agreea- 

 bly to the relations in which we 'nave viewed the preceding pieces, must 

 be a scapula; it is susceptible of considerable hinge like motion, and 

 appears to have been much less firmly attached to the costals than the 

 latter are to each other. 



A segment of a ennoid animal, which seems to have been a first costal 

 joint of .1 Pentacrinvs of Parkinson, occurred near the same place. 



22. Productus pectinuides. Sny. Convex valve, with a central longitu- 

 dinal indentation; the whole surface is longitudinally ribbed, each 

 rib being marked by two sti is, in addition to the central carina. 



The shell is notoffreque.it occurrence, and a perfect specimen has not 

 yet been obtained, but the portions we have examined, are sufficient 

 to show that it is perfectly distinct from either of the species we have 

 mentioned. We do not find any species figured or described by authors, 

 like it. 



23. Productus compressus. Say. Shell much compressed, with nume- 

 rous, acute striae, upwards of fifty in number on each valve, the alternate 

 ones rather smaller; a very flight central longitudinal indentation, on the 

 convex val»e; outline suborbicular; hinge edge rectilinear, shorter than 

 the greatest breadth of the shell. 



Greatest breadth, from 3-5 to 1 inch. In its proportions it resembles 

 the truncated portion of the productus of Martin, as represented on his 

 plate 22, fig. 3. It is very commoo. 



24. A shell of the length and breadth of three inches sometimes occurs, 

 the convex valve of which is transversely undulated, its umbo prominent, 

 and curved like that of a Gryphoea, its tip resting on the base of the oppo- 

 site valve, which is concave, with a transverse linear base; its muscular 

 impressions seem to have been lateral 



