REPORT OF THE STATE PALEONTOLOGIST I903 27I 



are in part ornamented with fine regular, rounded, and not crowded 

 granulations, while in others the raised granulations become quite 

 irregular in outHne and often confluent. The larger plates have each 

 a more or less prominent umbo, which may be central or excentric 

 and which together give various angular outlines to different por- 

 tions of the theca; there is usually a very large umbo between the 

 anus and the base. More or less wide, raised ridges usually connect 

 the umbones and many finer ridges run from them over the plate, 

 branch, cross the sutures and form some very fine reticulations hav- 

 ing rounded, depressed pits between them. 



Observations. This species differs from M . b a r r a n d i i in its 

 much smaller size, the excentric position of the anus, the outgrowth 

 of the theca to form a neck under the sigma, its conical base, its 

 prominent umbones and varied angular outlines. Mr Percy E. Ray- 

 mond writes me that the food grooves in the type specimens of M . 

 b a r r a n d i i are not so much elevated in proportion to the size of 

 the theca as in this Valcour form. 



These specimens are so well preserved that it seems proper to 

 make their description still more complete. Specimen A, which has 

 been chosen as the type, still bears two rings of the stem and shows 

 it to have had a marked and permanent bend toward the posterior 

 side. Another specimen has six rings of the stem still attached ; 

 these are circular, measure 1.2 mm across next to the theca and 

 uniformly taper down to .9 mm without alternations in size. The 

 outer surface of the joints is only gently convex and each joint is 

 very faintly and closely ribbed across its edge; there are about six 

 rings to the millimeter; here also a rather abrupt bend toward the 

 posterior side occurs next the theca and it is rather difficult to dis- 

 tinguish the sutures between the first two or three rings ; the lumen 

 is round and about half the diameter of the ring. The stem appears 

 to have been short and used perhaps as an anchor but not for com- 

 plete support. The theca probably rested, in part at least, on the 

 plates to the posterior of the proximal ring. This position would 

 place the mouth at the summit of the theca and bring the arms into 

 a horizontal plane and a similar external environment. Figures 4, 

 6 and 7, plate i, show three specimens oriented as if supported bv 



