A MONOGRAPH OF THE EXISTING CRINOIDS 183 



In a paper published iti 1908 I listed Cyllometra tigrina as among the crinoids of 

 southern Japan. In a revision of the family Himerometridae published in 1909 this 

 species was listed by me as Cyllometra tigrina. In my memoir on the crinoids of the 

 Indian Ocean published in 1912 I listed this form as Decametra tigrina and gave the 

 original reference and habitat. 



Dr. Clemens Hartlaub in his memoir on the comatulids of the Blake e.xpedition 

 published in 1912 described in detail and figured a specimen of Antedon tigrina from 

 the original lot from ?Kagoshuna Bay. This specimen had been sent by the Museum 

 of Comparative Zoology to Dr. P. H. Carpenter with the Blake collection, and after 

 Carpenter's death had been turned over to Hartlaub. 



In a paper on the crmoids of the British Museum published in 1913 I recorded a 

 specimen of Decametra tigrina from Toba Harbor, Japan, and two specimens, one large 

 and one small, from "Japan." Decametra tigrina was listed by me as an east Asiatic 

 species in 1913, and as a southern Japanese species in 1915. In my report on the 

 unstalked crinoids of the Siboga expedition published in 1918 I included tigrina in the 

 key to the species of Decametra and gave the habitat. 



In 1927 Dr. Torsten Gisl4n described Prometra perplexa from a large specimen from 

 Mortensen's station 10, at the same time assigning to his new species a smaller speci- 

 men from the same station. I cannot see that Prometra perplexa differs in any way 

 from P. tigrina, e.xcept that in the type specimen the longest cirri have a few more 

 segments than in the type specimen of tigrina. Undoubtedly Dr. Gisl^n faded to 

 recognize the identity of his specimens with my tigrina for the reason that in the 

 key to the genera of the family Colobometridae in the Siboga report his specimens 

 would fall in the genus Prometra, while in the same report I had included tigrina in the 

 genus Decametra. 



DECAMETRA ALAUDAE A. H. Clark 



Plate 23, Figures 114, 115 



Decametra alaudae A. H. Clark, Proc. U. S. Nat. Mus., vol. 40, 1911, p. 8 (southeast coast of Africa), 

 p. 33 (description; Cargados Carajos, 30 fms.); Crinoids of the Indian Ocean, 1912, p. 161 

 (synonymy ; locality) ; Smithsonian Misc. Coll., vol. 61, No. 15, 1913, p. 35 (published references 

 to specimens in the B. M.; description; locality); Unstalked crinoids of the ■Si6oja-Exped., 

 1918, p. 117 (in key; range); Journ. Linn. Soc. (Zool.), vol. 36, No. 249, May 1929, p. 642, 

 pi. 44, fig. 14 (Cargados Carajos; notes); John Murray Exped. 1933-34, Sci. Reports, vol. 4, 

 No. 4, 1936, p. 100 (range), p. 104. 



Diagnostic features. — The cirri are 12-14 mm. long with 26-28 segments, which 

 are subequal, from half again to twice as broad as long, the distal sometimes only 

 slightly broader than long; Pj is much larger, stouter, and stiffer than Pj, 9-12 mm. 

 long with 16-18 segments; P3 is similar to Pj, but smaller; the arms are 90-100 mm. 

 long. 



Description. — The cirri are XV, 26, small and slender. All the segments are 

 subequal, about twice as broad as long. 



The 10 arms are 90 mm. long and resemble those of D. taprobanes. 



P» is absent. Pi is slender and flagellate, 8 mm. long with 21 segments all of which 

 are about as long as broad. P2 is much larger, stouter, and stiffer, tapering very 

 gradually, 11 mm. long with 16 segments of which the fifth-seventh are half again 

 as long as broad and the remainder are about as long as broad or broader than long; 

 from the fourth onward the segments have projecting distal edges and distal angles 



