632 PEOCEEDINGS OF UNITED STATES NATIONAL MUSEUM. [1885, 



Pentacrinus Miilleri Oersted. 



P. H. Carpenter, loc. cit., p. 306. 



About oue huuclred specimens in all of tbis species were collected on 

 the two cruises, by far the greater number having- been obtained in 

 1885. The greatest length of arm observed was IGi™"^, with 134 joiuts, 

 the calyx and arms being exceptionally ])erfect, but the stem short. 

 Others nearly as large are contained in the collection. The longest 

 stem measures slightly more than 350°^"" in length, and includes 29 

 internodes, with 8 to 9 internodal joints ; the diameter of the stem is 

 5.5™°^ ; the length of the longest arm 135™™. The next longest stem 

 measures 280™™ in length, 5.5™™ in diameter, and has 25 internodes 

 with 9 internodal joints each. The shortest internodes observed occur 

 in a stem 222™™ long ; diameter of stem 5.8™™; number of internodes, 

 28 ; length of internodes, 7™™ ; number of internodal joints, 7. The 

 usual number of joints to an internode is 7 to 11, but as few as 5 and 6- 

 were noticed in some adult specimens. 



The stem differs greatly in shape, being sometimes very rounded 

 pentagonal, with but a slight longitudinal depression on each face, while 

 again this depression may be very wide and pronounced and the edges 

 quite angular. In the larger number of si^ecimens the internodal joints 

 are subequal in length, and in only a comparatively small number are 

 they regularly alternating, as thin and thick. In some specimens this 

 latter arrangement occurs irregularly on portions of the stem. 



The color varies greatly in alcoholic specimens, the variation being 

 probably due in part to the manner of preservation. Nearly half the 

 specimens have a tinge of green, yarying to bluish, this color being 

 sometimes very light, at others dark. Many specimens are very light 

 purplish, purplish white or yellowish white. Light shades of brown 

 and gra}^ also occur, and several varieties of coloring may be found on 

 the same specimen. The lower arm joints and calyx are generally 

 darker than the rest of the body, being often of a dark olive color. 



Comparatively few young specimens of Pentacrinus were obtained, 

 considering the large size of the entire collection made. From among the 

 young specimens examined about eight appear to belong to this species, 

 although where only short stems occur it is very difficult to distinguish 

 this species from P. decorus. A sufficiently complete series, ranging 

 from the largest to the smallest, has, however, been brought together, 

 to render the identifications i^resumably accurate. The differences 

 observed in the stems of adult specimens occur also among the young. 

 The internoflal joints are generally of subequal length, but in two speci- 

 mens thick and thin joints alternate, although the differences between 

 them are not very great. 



The youngest specimen in the lot and one of intermediate size fur- 

 nish the following measurements and other details : 



