630 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. [1865. 



specimens there are several which appear to resemble Rhizocrinus lofo- 

 tensis more or less closely as regards the joiuts of the stem, the shape of 

 the calyx, and the structure of the arras; but this resemblance is prob- 

 ably superficial, for the most extreme forms in this direction are con- 

 nected, by many specimens showing intermediate gradations, with speci- 

 mens that are typical of R. Raicsoni. Unfortunately R. lofotensis is very 

 poorly represented in the iJfational Museum collections, thereby i)reGlud- 

 ing careful comparisons with it. 



The entire collection exhibits a considerable range of variation, but 

 nothing beyond what has been already noticed by Dr. P. H. Carpenter, 

 unless it may be in the instance above mentioned. In nearly all the 

 specimens from the northern part of the Gulf of Mexico (stations 2399, 

 2401, 2403, 2403) the calyx is proportionally broad above, expanding 

 rather rapidly from the stem upward, and with scarcely ever any notice- 

 able restriction around the radials. The specimens from this region 

 are all very much alike as to the shape of the calyx, and in this partic- 

 ular differ from those taken off Havana (stations 2321, 2326, 2327, 2337, 

 2345) and south of Cuba (station 2129), in which the calyx is propor- 

 tionally longer and narrower with frequently a more pronounced radial 

 constriction. The stem is almost always smallest at the calyx, being 

 sometimes very small at that point ; quite perfect dice-box shaped 

 joints are not uncommon, especially low down on the stem ; the longest 

 joints scarcely ever exceed twice the diameter in length. 



Following are given measurements of three of the larger specimens 

 from station 2401. The arms are perfectly preserved only in No. 1. 



Dimensions of three large specimens from station 2401. 



No. 1. 



No. 2. 



No. 3. 



IiCnortli of stem 



If umber of joints in stem 



lengtli of stem joiuts near middle. 



Diameter of s-ame 



Height of basal tube 



Oreatest diame. er of same 



Height of calyx 



Gieatest diameter of same 



i,engtli of arms 



Number of double joints in same . . 



. millimeters - 



.millimeters. 



do 



do 



do 



do 



do 



do 



190 

 74 

 .3 

 1.5 



4 



2.8 

 5 

 3 



45 

 About 42 



248 

 96 

 2.6 

 1.5 

 3.8 

 2.8 

 4.8 

 3 



280 



W6 

 3 



1.9 

 3.5 

 2.5 

 4.5 

 2.9 



RECORD OF SPECIMENS 



Gulf of Mexico, southeast of Pensacola, Fla. : 



Latitude 28° 44' N., longitude 86° 18'' W., 196 fathoms, gy. M. ; station 2399, 



two specimens (12348).* 

 Latitude 28° 38' 30" N., longitude 85° 52' 30" W., 142 fathoms, gu. M. brk. Sh.; 



station 2401, one hundred specimens (12354). 

 Latitude 28° 36' N., longitude 85° 33' 30" W., Ill fathoms, gy. M. ; statiou 2402, 



three speciuiens (12352). 

 Latitude 28*^ 42' 30" N., longitude 85° 29' W., 88 fathoms, gy. M. ; station 2403, 



one specimen (12349). 



The numbers in parentheses are catalogue numbers of the U. S. National Museum. 



