180 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



and less uniform distribution of spines on the dorsal surface of the elements of the 

 division series. 



THALASSOMETRA MULTISPINA (P. H. Carpenter) 



Antedon multispina P. H. CARPENTER, Challenger Reports, Zoology, vol. 26, part 60, 1888, p. 117 (de- 

 scription; station 344), p. 248 (description; station 344 [but not station 135G=7%. setosa]), 

 pi. 13, figs. 1-3, pi. 69, figs. 1-4 [not pi. 14, figs. 5-7=Koehlermetra porrecta, or pi. 50, figs. 3-6= 

 Th. setosa]; Journ. Linn. Soc. (Zool.), vol. 24, 1891, p. 66 (comparison with [Stiremetra] lusi- 

 tanica). HARTLAUB, Bull. Mus. Comp. Zool., vol. 27, No. 4, 1895, p. 131 (in Basicurva group; 

 bathymetric relationships), pp. 134, 136 (comparison with Th. agassizii). LANG, Text book of 

 comparative anatomy, 1896, vol. 2, p. 375, fig. 326D. MINCKERT, Arch. Naturg., Jahrg. 71, 

 1905, vol. 1, Heft 1, pp. 170 and following (syzygies; regeneration). HAMANN, Bronn's Klassen 

 und Ordnungen des Tier-Reichs, vol. 2, Abt. 3, 1907, pp. 1578, 1582 (listed). HARTLAUB, Mem. 

 Mus. Comp. Zool., vol. 27, No. 4, 1912, p. 285 (in the Granulifera group; doubtless different from 

 granulifera), p. 286 (referred by Clark to the Thalassometrinae) . 



Thalassometra multispina A. H. CLARK, Smithsonian Misc. Coll., vol. 50, pt. 3, 1907, p. 360 (listed) ; 

 Amer. Nat., vol. 42, No. 500, 1908, p. 542 (belongs to a group characteristic of the oceanic area); 

 Geogr. Journ., vol. 32, No. 6, 1908, p. 603 (same) ; Proc. Biol. Soc. Washington, vol. 22, 1909, 

 p. 14 (listed); Proc. U. S. Nat. Mus., vol. 40, 1911, p. 8 (west coast of Africa), p. 38 (synonymy; 

 near Ascension, 420 fathoms, volcanic sand) ; Smithsonian Misc. Coll., vol. 61, No. 15, 1913, 

 p. 47 (published references to specimens in the B. M. ; Challenger Sta. 344 [but not 135= Th. 

 setosa]; notes); Unstalked crinoids of the Siboga-Exped., 1918, p. 166 (in key; range), p. 171 

 (references); The Danish Ingolf-Exped., vol. 4, No. 5, Crinoidea, 1923, p. 40 (range). GISLEN^ 

 Ark. Zool., vol. 19, No. 32, Feb. 20, 1928, p. 6, No. 24 (notes on specimens in the British Museum) 

 A. H. CLARK, Journ. Linn. Soc. (Zool.), vol. 36, No. 249, April 1929, p. 654 (compared with 

 Th. peripolos, sp.nov.). GISLEN, Kungl. Fysiogr. Sallsk. Handl., new ser., vol. 45, No. 11, 1934^ 

 p. 22. 



Diagnostic features . The cirri are arranged in 15 crowded columns on the centro- 

 dorsal; the elements of the division series and lower brachials have numerous fine spines 

 on the dorsal surface. The 10-12 arms are 50 mm. long, and the cirri have 25-30 

 segments. 



Description. The centrodorsal is low-hemispherical. From the figures the cirrus 

 sockets appear to be arranged in 15 columns, but the surface of the centrodorsal is not 

 differentiated into radial areas. 



The cirri are about XX, 25-30; a few of the segments are longer than broad, and 

 the remainder are shorter and overlap slightly so as to develop a dorsal spine. 



The radials are not visible in the adult. The IBr t in the adult are very short, and 

 the IBr 2 (axillaries) are widely pentagonal. The axillaries and first brachials have 

 flattened outer sides and straight lateral edges, and the inner side of the second brachial 

 and of the hypozygals of the first syzygial pair are also flattened. There are numbers 

 of small spines on the elements of the IBr series and arm bases. The IIBr series, when 

 present, are 4(3+4) and resemble the IBr series. 



The 10-12 arms are probably about 50 mm. long. Of the four specimens described 

 by Carpenter three had 10 arms and one had 12, with two IIBr 4(3+4) series present. 

 The brachials are elongately quadrate with tufts of numerous small spines at one or 

 both ends. 



Syzygies occur between brachials 3+4, again from between brachials 10 + 11 to 

 between brachials 15+16, and distally at intervals of 4 or 5 muscular articulations. 

 In arms arising from a IIBr 4(3+4) series the first syzygy is between brachials 1 + 2. 



