766 BULLETIN 82, UNITED STATES NATIONAL MUSEUM. 



PLATE 35. 

 Pentacrinoid lance of Hathrometra sarsii. (After M. Sars.) 



FIG. 1216. Pentacrlnoid at stage at which six brachials are present 



1217. Pentacrlnoid at stage at which pinnules are just beginning to appear. 

 1218. Pentaerinoid at stage at which cirri are beginning to appear. 

 1219. Fully developed pentacrinoid. 



PLATE 36. 

 Pentacrinoid larva of Hathrometra sarsii. (After M. Sars.) 



FIG. 1220. Most highly developed pentacrinoid obtained by Professor Sars. 

 1221. Part of arm of same individual taken from middle. 

 1222. Summit of column of fully developed individual. 



1223. Tip of arm of young pentacrinoid, showing development of first pinnule to appear. 

 1224. Sixth pinnule of individual shown in fig. 1220. 

 1225. Disk of fully developed pentacrinoid. 



PLATE 37. 



FIG. 1226. Pentacrinoid of Heliometra glacialis. (After Levinsen.) 



1227. Pentacrinoid of Hathrometra prolixa from Jan Mayen. (After P. H. Carpenter. ) 



1228. Pentaerinoid of Ptilometra miilleri. (After H. L. Clark.) 



1229. Same. (After H. L. Clark.) 



1230. Same. (After H. L. Clark.) 



1231. Abnormal arm of a specimen of Heliometra glacialis. (After Levinsen.) 



PLATE 38. 

 Pentacrinoid larvw and pinnules of viviparous comattiliiln. (After Th. Mortensen.) 



FIG. 1232. Thaumatometra nutria;, a fully grown peutacrinoid attached to third segment of 



genital pinnule; in ovary eggs are visible. 

 1233. Thaumatometra nutrix, genital pinnule with young pentacrinoid attached to pinnule 



segment protruding through opening of the m.-irsupiurn. 

 1234. Thaumatometra nutrix, genital pinnule with two pentnorinoids attached to third 



pinnule segment protruding from marsupium. 

 1235. Thaumatometra nutrix, type specimen, viewed dorsally; on one of arms to the left 



Is genital pinnule bearing large pentacrinoid. 



1236. Thaumatometra nutrix, genital pinnule with egg in marsupium. 

 1237. Thaumatometra nutrix, genital pinnule with young pentacrinoid attached to extreme 



edge of marsupium. 

 1238. Iometra viriparrt, jienitMl pinnule viewed ventrally showing slltlike opening of 



marsupium. 



1239. Isometra vivipara, male genital pinnule. 

 1240. Isomelra riripara, proximal portion of arm, showing oral pinnules and extra fourth 



pinnule, 



PLATE 39. 



Commensals of Crinoids. 



Fios. 1241-1245. rjiifitmmt'lla antednnix. (After Mortensen.) 

 1246-1248. PachyJasma crinoidophilum. (After Pllsbry.) 

 1249, 1260. Verruca nltida. (After Hoek.) 



