A MONOGRAPH OF THE EXISTING CRINOIDS 295 



trig gradually and becoming slender in its distal third, with 26 segments, which at first 

 are twice as broad as long, becoming as long as broad after the ninth and somewhat 

 longer than broad in the terminal portion ; the first seven or eight segments are rather 

 strongly carinate, and in addition have a low sharp ridge running along the exterior 

 surface at the base of the carinate processes. P 2 is similar to Pi and of the same length, 

 but the low ridge just described may be traced to about the twelfth segment. P 3 is 

 9 mm. long, with 19 segments, similar to the two preceding pinnules but slightly less 

 stout: P 4 is small, 6 mm. long, tapering rapidly in the proximal half and becoming 

 very slender distally, with 1 6 segments, which at first are twice as broad as long, becom- 

 ing as long as broad on about the ninth, and longer than broad distally; the first six 

 segments are carinate like those of the preceding pinnules. P 6 is similar, 5.5 or 5.0 mm. 

 long. P 6 and the following pinnules are 6 mm. long with 17 segments, which at first 

 are twice as broad as long, becoming about as long as broad on about the eighth, and 

 twice as long as broad terminally; the pinnules are about as stout basally as the two 

 preceding, tapering rapidly in the proximal half and becoming very slender distally; 

 the carination of the proximal segments is slightly marked on the first four, later 

 becoming restricted to the second and third segments only, and disappearing entirely 

 from the pinnules in the outer half of the arm. 



Near their tips the ambulacra] lappets contain very minute calcareous reticula- 

 tions of one, two, or three meshes; the perisome between the sacculi and thepinnulars 

 is unplated. 



The tentacles contain two narrow lines of spicules, one distal and one proximal, 

 which extend to about the end of their proximal half. 



Locality. — Investigator; Pedro shoal, off the western coast of India, west of Man- 

 galore [A. H. Clark, 1909, 1912] (9, U.S.N.M., 35088 [original No. 3F], 35178 [origi- 

 nal No. 6F], 35184 [original No. 11F], 35192 [original No. 7F], 35209 [original No. 8F], 

 35210 [original No. 2F]; I. M.). 



History. — This species was first described in 1909 and was redescribed and figured 

 in 1912. It is as yet known only from the nine specimens collected by the Investigator 

 on Pedro Shoal. 



HETEKOMETKA MADAGASCARENSIS (A. H. Clark) 



Plate 29, Figures 120-122 



Craspedometra madagascarensis A. H. Clark, Proc. U. S. Nat. Mus., vol. 40, 1911, p. 8 (southeastern 

 Africa), p. 23 (description; Madagascar); vol. 43, 1912, p. 3S1 (cotype in the U.S.N. M.), p. 384 

 (original reference), p. 393 (Madagascar; description of specimens other than the type); 

 Crinoids of the Indian Ocean, 1912, p. 119 (synonymy; Madagascar). 



Heterometra 7nadagascarensis A. II. Clark, Unstalked crinoids of the Siboga-Exped., 1918, p. 78 (in 

 key; range) ; John Murray Exped. 1933-34, Sci. Reports, vol. 4, No. 4, 1936, p. 99 (range), p. 104. 



Heterometra madagascariensis Gislen, Kungl. Fysiogr. Sallsk. Handl., new ser., vol. 45, No. 11, 

 1934, pp. 22, 4S. 



Diagnostic features. — The brachials are distinctly wedge-shaped, with the ends 

 never quite parallel, and are not exceedingly short. The enlarged lower pinnules are 

 smooth, with the earlier segments keeled. The cirri are 25-30 mm. long with 34-36 

 segments of which the longest are somewhat longer than broad and the outer are 

 broader than long and bear small but prominent dorsal spines. The 16 arms are 130 

 mm. long. P 2 is 12 nun. long, with 27 segments. P 3 is similar to P 2 but is very slightly 

 larger and longer. 



