MUSEUM OF COMPARATIVE ZOOLOGY, 218 
DESCRIPTION OF A YOUNG HOLOPUS. 
A very young specimen of Holopus was dredged in tho “ Blake” Ex- 
pedition in Lat. 23? 1’ N., Long. 83° 14' W. Depth 100 fathoms. It 
has been sent to Professor Sir Wyville Thomson for study, but was pre- 
viously drawn by Mr. Agassiz for the accompanying plate. 
The specimen is attached to a piece of rock, and was not detected 
until it had become dry. The general shape is a truncated cone when 
contracted, with irregular contour of attachment. The body part is 
very short, spreading out a little at the foot; surface granulated or 
shagreen-like, with a few small tubercles scattered over it. No trace 
of divisions can be detected in this part. Above, there are two circles of 
five plates each, fitting closely together and concealing the arms entirely. 
The lower plates are pentagonal with rounded corners, the upper and 
lower sides being parallel. The lower sides do not form a continuous line 
from plate to plate, so that there are small triangular spaces left be- 
tween them, There is a row of tubercles on each side of a plate, and 
one in the middle forming a ridge which projects a little downward over 
the lower edge of the plate. On the upper edge of these plates are 
articulated five smaller triangular ones, firmly closed together. "They 
have also a ridge in the middle in continuation of the ridge in the lower 
plates. The larger pentagonal plates are the radial axillaries of Sir 
Wyville Thomson, but the smaller triangular ones seem to become fused 
with them in the adult. Color black. Diameter at base 3 mm., height 
a little over 1 mm, 
Prater II. 
Young Holopus from above and in profile, magnified about eighteen 
diameters. 
