A MONOGRAPH OF THE EXISTING CRINOIDS 239 



var. erinacea in an appendix to my memoir on the crinoids of the Indian Ocean pub- 

 lished in 1912. In my report on the crinoids of the Siboga expedition published in 

 1918, I included erinacea in the key to the species of Oligometra, giving northeastern 

 Ceylon as the habitat. 



OLIGOMETRA SERRIPINNA var. OCCIDENTAL1S A. H. Clark 



PLATE 26, FIGURE 136; PLATE 28, FIGURES 150, 151; PLATE 30, FIGURE 163 



Oligometra serripinna var. occidentalis A. H. CLARK, Proc. TJ. S. Nat. Mus., vol. 40, 1911, p. 3 

 (synonymy; Mauritius; Cargados Carajos; 0-30 fms.; characters); vol. 43, 1912, p. 384; 

 Crinoids of the Indian Ocean, 1912, p. 174 (synonymy; localities) ; John Murray Exped. 1933-34, 

 Sci. Reports, vol. 4, No. 4, 1936, p. 90 (Mabahiss stations 10, 27, 45; notes; range), p. 101. 



Oligometra occidentalis A. H. CLARK, Smithsonian Misc. Coll., vol. 60, No. 10, 1912, p. 28 (resembles 

 specimens of serripinna from Tonga; distribution of this type); Proc. U. S. Nat. Mus., vol. 43, 

 1912, p. 382 (cotype from Bagamoyo in U. S. N. M.); Smithsonian Misc. Coll., vol. 61, 

 No. 15, 1913, p. 38 (published reference to specimens in the B. M.; locality; notes); Unstalked 

 crinoids of the Siboga- Exped., 1918, p. 129 (in key; range); John Murray Exped. 1933-34, Sci. 

 Reports, vol. 4, No. 4, 1936, p. 87 (listed), p. 104. 



Oligometra serripinna occidentalis A. H. CLARK, Proc. U. S. Nat. Mus., vol. 43, 1912, p. 401 (Fouquet 

 Island, near Mauritius; Bagamoyo). HARTMEYER, Mitt. Zool. Mus. Berlin, vol. 8, No. 2, 1916, 

 p. 236 (Fouquet Island, No. 5101 ; specimen from Bagamoyo in U. S. N. M.) . 



Diagnostic features. The segments of the pinnules following P 2 have rather 

 strongly projecting distal edges and angles; the lateral processes on the distal ends 

 of the outer segments of P 2 are only slightly developed. 



Description. The cirri are XIV-XVII, 18-22 (usually 19-20). The distal 

 segments are about as long as broad. 



The 10 arms are 70-80 mm. long. 



P 2 is much larger than PI or P 3 and is composed of 19 segments most of which are 

 about as long as broad, or slightly longer than broad. The lateral processes on the 

 distal ends of the outer segments are only slightly developed, and are small and 

 delicate. The segments of the pinnules succeeding P 2 have rather strongly projecting 

 distal edges and angles. 



Notes. The preceding description is based upon the nine specimens from Car- 

 gados Carajos. 



In the specimen from Mauritius the cirri are XVI, 17, 9 mm. long. The arms are 

 about 55 mm. long. P 2 is 7 mm. long with about 15 segments. The lower pinnules 

 exhibit almost none of the peculiar expansion of the distal ends of the segments from 

 which serripinna gets its name, there being merely a small process ending in a tuft of 

 very fine spines at the three distal angles. 



Both the specimens from Mabahiss station 45 are small, and in both P a is absent 

 One of them has the arms 25 mm. long. 



One of the specimens from Mabahiss station 27 has the arms 55 mm. long and the 

 cirri XIV, 14-15. P 2 has 13 segments of which the outer have the prismatic angles 

 very slightly produced. The other specimen from station 27 has the arms 50 mm. 

 long and the cirri XI, 13-14. P 2 has 12 segments, the outer with a very slight pro- 

 duction of the prismatic angles. 



The specimen from Mabahiss station 10 consists of arm fragments from a large 

 individual. 



