118 



THREE CRUISES OF THE " BLAKE." 



mens the cirri of which had become attached to adjoining steins. 

 It is possible that they may live gregariously, more or less united 

 either by the twisting of the stems or the grappling of the cirri, 

 and be only loosely attached to the ooze on which they live, or 

 anchored more securely by the terminal whorl to some project- 

 ing piece of rock or gorgonia stem. 



Crinoids both stalked and free live in colonies. Comatulae 



are most abundant in certain local- 

 ities. Antedon /Sarsii was brought 

 up in thousands by the " Blake." 

 The U. S. Fish Commission and 

 the " Challenger ' have had a sim- 

 ilar experience with different spe- 

 cies of Comatulae. On one occa- 

 sion, off Sand Key, we must have 

 passed over a field of Rhizocrinus 

 with the dredge, judging from the 

 number of stems and heads of all 

 sizes it contained. The oldest species 

 known, Pentacrinus asterius (Fig. 

 405), is marked by its greatly mul- 

 tiplied large and strong arms, while 

 in P. decorus (Fig. 407) the num- 

 ber is greatly reduced. We know 

 but little of the young of Pentacri- 

 nus. The youngest specimens 

 dredged by the " Blake," and fig- 

 ured by Carpenter (Fig. 408), show 

 the great relative height of the stem 

 joint as a characteristic feature of 

 young specimens. The stems of 



Fig. 408. Pentacrinus decorus. 

 (Carpenter.) 



Pentacrinus asterius and P. decorus are longer than those of 



O 



the other species of the genus. P. Mulleri (Fig. 409) was dis- 

 covered by Oersted, and in 1865 Dr. Liitken gave a detailed 

 account of the West Indian Pentacrinidse ; the many speci- 

 mens of Pentacrinus dredged by the " Blake " were originally 

 identified with it, but, as has been clearly shown by Carpenter, 

 they all belong to P. decorus. Both P. Mulleri and P. 



