GYMNOPATAGUS MAGNUS. 231 



Gymnopatagus magnus. 



A. Agassiz and Clark, 1907. Bull. M. C. Z., 61, p. 133. 



Plates 146, fig. 13; 159, fig. /. 



After the very elaborate and minute description which Koehler (1914. Ech. 

 Indian Mus. Spat., p. 98-105) has given this species under the name G. sewelli, 

 it would be quite superfluous to go into any details here. The photograph 

 (PL 159, fig. 1) of the holotype, may be of interest to compare with Koehler's 

 PL 13, fig. 4. The Investigator specimens were larger than those taken by the 

 Albatross but in spite of that fact, the differences are so trivial, it is difficult to 

 see why Dr. Koehler did not call his specimens magnus. The original description 

 of G. magnus is seemingly sufficient to have enabled Koehler to recognize the 

 species in the specimens he had in hand. 



As regards the pedicellariae, my observations agree with Koehler's in nearly 

 every particular. The complete absence of ophicephalous pedicellariae is quite 

 remarkable. I have found a single globiferous pedicellariae, the only one as 

 yet seen on any member of the genus. The stalk was made up of parallel fibres 

 for most of its length, somewhat as in the Arbaciidae, but was conspicuously 

 enlarged and compact both at the base and tip; it was 5 or 6 times as long as 

 the head. The valves (PL 146, fig. 18) were about .63 mm. long, with narrow 

 blade having several big teeth near the tip. In addition to this unique pedicel- 

 laria, I found several of the a slender-tridentate " type with 4 valves each, a 

 variant of which Koehler does not speak. 



Besides being the giant of the genus, this species is of interest because it 

 is the only one which agrees with valdiviae in having the anterior ambulacrum 

 distinctly sunken. It is a well-marked species because in addition to this char- 

 acteristic test-form, it has such a large number of primary tubercles and spines 

 dorsally in all the interambulacra. Attention should be called to the fact that 

 valdiviae and magnus are inhabitants of much deeper water than the other 

 members of the genus. 



Station 5082. Off Omai Saki Light, Japan. Bott. temp. 37.7°. 662 fms. 

 Gn. m., fne. s., glob. 



Station 5083. Off Omai Saki Light, Japan. Bott, temp. 38.1°. 624 fms. 

 Fne. gy. s., glob. 



Four specimens. 



