PART 5 A MONOGRAPH OF THE EXISTING CRIXOIDS 743 



Inst. Fish. Oceanogr., Vladivostok, vol. 30, 1949, p. 13 (in key). — GiSLfiN, Rep. Swedish Deep 

 Sea Exped., vol. 2, Zool., No. 4, 1951, pp. 55, 56. 

 Trichotnetra (part) A. H. Clark, Crinoids of the Indian Ocean, 1912, p. 240. 



Diagnosis. — A genus of Bathynictrinae in which the cirri are at least XXV in 

 number with 10 to 22 segments, all of which but the fu-st one are longer than broad; 

 Pi has up to 20 segments in all the species except tenuis, where it has about 35; P2 may 

 be longer but is usuallj^ a little shorter than Pi. 



Type species. — Antedon ciliata A. H. Clark, 1907, a sjmonym of A. tenuis A. H. 

 Clark, 1907. 



Geographical range. — From the region of Marion Island in the Southern Ocean, 

 southern India, the East Indies, southern and northern Japan, the colder parts of the 

 Sea of Japan and the Gulf of Tartary, the western Aleutian Islands, Panama, the Ker- 

 madec Islands and northeast New Zealand, and in the Atlantic from Iceland to the Davis 

 Strait and from Brazil. 



Batbymetrical range. — From 146 to 3239 meters. 



Thermal range.— From 0.39° C. to 5.95° C. 



Remarks [by A.M.C.]. — A re-examination of the type specimen of Thaumatometra 

 cypris A. H. Clark, 1913, has revealed no significant differences between it and T. parva 

 A. H. Clark, 1908, in my opinion. Both types were from Sagami Bay, Japan. T. cypris 

 therefore becomes a synonym. 



Unfortunately many of the species of Thaumatometra are only known from one or 

 a very few specimens. The following key should therefore be used with reservations 

 since some of the characters contained in it, particularly the number and proportions 

 of the cirrus segments as well as of the cirri themselves, tend to vary with size and to 

 some extent individually. T. plana from off southern India has been removed from 

 the key since its cirri are unknown. It is distinguished by having the centrodorsal 

 much flattened, LV-LX cirri and a rather small number of segments in the proximal 

 pinnules. Pi having 13 in the type specimen and P2 only 8. 



As explained under the heading of Fariometra, I have removed the species Tliauma- 

 tometra sokotrae John, 1937, to that genus. 



KEY TO THE SPECIES OF THAUMATOMETRA 



(For T. plana from the Laccadive Sea, see remarks above, and page 765.) 



a'. Size large, the arms 110-130 mm. long; Pi 20 mm. long with about 35 segments of which the 

 proximal 12 are short and broad, mostly broader than long, and the remainder are elongated and 

 slender; Pj slighth' shorter with 20 segments of which the two basal are broader than long and 

 the remaining ones are much elongated, the basal 10 segments carinate; the following pinnules 

 similar to Pj (Gulf of Tartary and the Sea of Japan south to Nanao, Japan, and Cape Duroch, 



Korea ; 146- 1 500 meters) tenuis (p. 744) 



a-. Smaller, the arms not known to exceed 70 mm. in length and rarely over 40 mm.; Pj with not more 



than 20 segments. 



6'. Cirrus segments much elongated, subequal, the antepenultimate about three times as long as 



the proximal width, the penultimate twice as long as broad; distal edges of the cirrus segments 



much expanded. 



c'. Cirri about XXX, 15-18; arms 30-40 mm. long; Pjwith a gonad (between Marion Island and 



the Crozcts, Southern Ocean; 2925 meters) abyssorum (p. 749) 



c'. Cirri about XLV, 12-15; arms about 13 mm. long in the unique holotypo; P3 bears the first 



gonad (coast of Brazil; 1495 meters) minutissima (p. 751) 



6". Earlier cirrus segments much elongated, but the distal shorter so that the antepenultimate is 

 not more than twice as long as its proximal width and the penultimate is shorter. 



