768 BULLETIN 82, UNITED STATES NATIONAL MUSEUM. 



Fios. 1296, 1297. Two views of cyst on arm of Comactinia meridionals containing ifysostomum 



cysticolum. 

 1298, 1299. Two cysts on arm of Pachylometra invqitalte containing Myzostomum tenutepi- 



num. 

 1300. Stalked cyst from disk of Adelometra angustiradia containing Myzostomum 



murrayi. 



1301. Cyst containing Myzostomum murrayi on specimen of Stiremetra breviradia. 

 1302-1304. Three views of cyst from arm of Pachylometra iniequalis containing Uyzosto- 

 mum tenuispinum; flg. 1304 cyst broken open to show the female and the 

 dwarf male within. 

 1305. Pinnule cyst not caused by myzostome from specimen of Antedon biflda from 



Kenmaes Bay. 



1306. Egg-like contents of a pinnule cyst from specimen of Antedon bifida from 

 Cumbrae: the right side is drawn in surface view, left side in optical sec- 

 tion with cortical layer and the internal mass. 

 1307. Pinnule cyst not caused by a myzostome from specimen of Antedon bifida from 



off Keumaea Bay. 



1308. Three deformities from specimen of an Antedon dredged by the Vettor Pisani 

 at Gibraltar; a, groove-like deformity; b, pinnule cyst; and c, arm swelling. 



PLATE 45. 



Fio. 1309. Skeleton of central portion of a young Antedon biflda viewed dorsally with eemtro- 

 dorsal removed, showing central canal enlarged by absorption of part of original 

 basals, though nearer cavity of calyx, still contracted by secondary endogenous 

 growth; primary nerve stems and courses of their derivatives shown. (After 

 W. B. Carpenter.) 



1310. Same, viewed ventrally, with rndianal added. (After W. B. Carpenter.) 



1311. Central portion of Leptoinetra, celtica after removal of visceral masa (After P. H. 

 Carpenter. ) 



1312. Arm of specimen of Antedon bifida in which the IBn (axillary) is lacking, first bra- 

 chial of free undivided arm immediately following IBn. (After W. B. Carpenter.) 



1313.- Dorsal view of skeleton of terminal portion of arm of mature pentacrlnoid of Antedon 

 biflda. (After W. B. Carpenter.) 



1314. Ventral view of same. (After W. B. Carpenter.) 



PLATE 46. 



FIG. 1315. Section of gastrula of Antedon mediterranea early on the second day. (After Uury.) 

 1316. longitudinal vertical section of later gastrula (end of second day) of Antedon 



mediterranea, showing formation of mesoblast (After Bury.) 

 1317. Diagram of structure of adult sacculus. (After Bury.) 



131 8. Pyrifonn sues with refractive spherules from sacculi at different ages. (After Bury.) 

 1.T19. Transverse sections of two pyriform sacs from sacculi taken from adult specimens 



of Antedon mediterranea. (After Bury.) 



1320. Part of transverse section of eleventh day larva, showing development of sac- 

 culus. (After Bury.) 



1321. Part of transverse section through same region about twentieth day. (After Bury.) 

 1322. Arm pair of fully grown pentncrinoid of Hathrometra sarsii, showing regenerating 

 :irm. (After M. S:ir-;. ) 



PLATE 47. 



Vio. 1323. Horizontal section of calyx and arm bases of Antedon bifida, flattened out, showing 



axJal camils. (After W. IV Carpenter.) 



1324. Central portion of Coma tula pectinatn after removal of visceral mass. (After P. H. 

 Carpenter.) 



