MUSEUM OF COMPARATIVE ZOOLOGY. 167 



on the anal interradii. The stem was somewhat curved at the upper 

 extremity, the terminal joints expanding slightly to form a continuation 

 of the outline of the cup of the base of the calyx. The stem tapered 

 very gradually, and in its general appearance recalled that of Apiocrinus, 

 expanding again towards the base, the root of which, however, was not 

 obtained by the "Albatross." The stem is cylindrical, without cirri. In 

 the upper third the joints are alternately ribbed transversely, or even 

 ornamented near the base of the calyx with more or less prominent 

 tubercles, as in Millericrinus. The uppermost joint is convex, and in 

 the space left vacant between it and the central part of the basal ring 

 a small lobed delicately reticulated pentagonal disk was found resting 

 upon the upper face of the " article basal " of De Loriol. This is prob- 

 ably a modified anchylosed infrabasal ring, which may or may not be 

 resorbed iu older stages of the genus. 



There are five distinct basals in one of the specimens ; in the second 

 their sutures can fairly be distinguished, while in the third they were 

 completely anchylosed, much as they so frequently are in Rhizocrinus. 

 As in Hyocrinus, the basals are about half the height of the first radials ; 

 the second radials cut deeply into the first radials. 



The stem of this crinoid must have attained a length of from 26 to 

 27 inches; the height of the calyx to the interradials is -^ of an inch; 

 its diameter at the inner base of the second radials is \^ of an inch, at 

 the height of the third joint of the second pinnule 1 inch, at the level of 

 the proximal face of the radials § of an inch, and at the level of the su- 

 ture of the basals with the uppermost joint \ of an inch ; and the length 

 of the arms is probably about 8 inches. 



I propose to name this crinoid Calamocrinus Diomedas, after the ves- 

 sel which discovered it. I have to thank Colonel Marshall McDonald, 

 the U. S. Fish Commissioner, for the opportunity of studying this 

 crinoid. With his consent, a detailed account of Calamocrinus will 

 be published in the Museum Memoirs as soon as the plates can be 

 prepared. 



Cambridge, November 28, 1890. 



