18 



to furnish the genital lacunse of the arms (PL lY., fig. 41, 

 gen. Ic). 



Corpuscles. — Under the term " corpuscles sanguins," 

 Cuenot (5) has described three kinds of amoeboid cells which 

 occur in the various tissues and coelomic fluid of Antedon : 

 (1) amoebocytes with short pseudopodia ; (2) amoebocytes 

 of extremely elongated form which are often found 

 migrating in the tissues, but which ultimately become 

 filled with rod-like bodies which have a special affinity 

 for salfranine, when the cell assumes a rounded form; 

 (3) very slightly amoeboid cells crowded with granules 

 which are golden yellow in the living animal. These are 

 the " oil cells " of Wyville Thomson, and they often occur 

 in numbers amongst the cells of the ectoderm, as well as 

 in the stroma of the skeletal plates. The rounded cells 

 described above as occurring amongst the fusiform cells 

 of the intestinal epithelium may possibly belong to the 

 first of these groups. 



The Ccelom. 



In Antedon, as in other Crinoidea, the cavity of the 

 coelom is not a clear space like that of the Echinoidea and 

 Holothuroidea, but is traversed in all directions by 

 trabeculse of connective tissue lined by coelomic endothe- 

 lium. The cavity is further partitioned by lamellae of 

 connective tissue which lie parallel to the body-wall into 

 two well-defined but intercommunicating sub-cavities — 

 the peripheral, or subtegumentary, and the peri-intestinal. 

 The latter encloses the intestine, which coils around a 

 central clear space which nearly coincides with the vertical 

 axis of the disc, and is known as the axial sinus (PL V., 

 fig. 52, ax. si.). The upper, or oral, end of this sinus 

 communicates directly with the subtentacular canals of 

 the arms (fig. 52; PL III., fig. 29; PL IY.,fig. 41, s.te.ca.). 



