PART 5 A MONOGRAPH OF THE EXISTING CRIXOIDS 297 



the thii'd is of about the same proportions as the second, and the following gradually 

 mcrcasp. in length so that those following the eighth are about as long as broad. In 

 the distal third of the pinnule the segments have the outer side somewhat produced into 

 a rounded or bluntly angular swelling giving the outer profile a scalloped or serrate 

 appearance which, when well-developed, suggests a rudimentary terminal comb. 



Po is of the same length as P, and resembles it; the segments number 45 and are 

 relatively slightly longer. 



P3 is from 15 to 20 nun. long, tapering more gradually than the precedmg pinnules, 

 with 27 segments of which the outer become twice as long as broad and lack the pro- 

 duction of the outer side. P4 is 12 mm. long with 23 segments, resembling P3 but with 

 the segments slightly longer. Pj is 12 mm. long with 20 segments, resembling P4 but 

 with the outer segments still more elongate, nearly 3 times as long as broad. The fol- 

 lowing pinnules are of about the same length, but taper still more gradually and thus 

 appear stouter. 



The distal pinnules are slender, IS mm. long with 24 segments which become twice 

 as long as broad on the sixth or seventh and 3 times as long as broad terminally. 



The preceding description is based mainly upon the specimens collected by the 

 Mission scientifique du Cap Horn, in the Paris Museum. 



Notes. — -A small specimen from Sta. 100, Mission scientifique du Cap Horn, does 

 not differ essentially from the adults. The axillaries are more rhombic with the anterior 

 angles less produced, and the brachials are relatively longer, the first syzygial pair being 

 about as long as broad. The relationships between Pi and Pj are the same as in the 

 adults. 



[Notes by A.M.C] The type specimen in the British Museum also has a deep pit 

 at the apex of the centrodorsal. The cirri are about LXXV, 45 and about 45 mm. long. 

 The arms were probably about 150 ram. long and are 2.5 mm. wide at the first syzygy. 

 The length from the proximal edge of the IBri to the second syzygy (9 + 10) is 15.5 mm. 

 Not one Pj remains intact; the longest remaining one has 49 segments, and probably 

 had at least a dozen more; P2 has about 47 segments and measures 21 mm. 



One of the two specimens from the Valparaiso-Concepci6n cable has the arms over 

 180 mm. long. The centrodorsal is 7.0 mm. in basal diameter and 3.5 mm. in height. 

 The width of the arms at the first syzygy is 2.6 mm. and the length from IBrj to the 

 second syzygy 16.0 mm. The cirri number about XC, the longest have 65 segments 

 and are 65 mm. in length. P, has about 46 segments and measures 21 mm. and Pj is 

 the same. The Sylvia specimen though somewhat smaller (IBri to the second syzygy 

 measuring 13.5 mm.) has about 100 cirri, the longest of them with about 48 segments; 

 the centrodorsal is 6.5 mm. by 4.5 mm. 



Localities. — Challenger station 308; off Tom Bay, Patagonia (lat. 50°08'30" S., 

 long. 74°41'00" W.); 320 meters; blue mud; January 5, 1876 [P. H. Carpenter, 1888; 

 A. H. Clark, 1913] (1, B.M.). 



Challenger; Tom Bay, Patagonia [P. H. Carpenter, 1888; A. H. Clark, 1913] (1, 

 B.M.). 



Smyth Channel, Straits of Magellan; Dr. H. Rehberg [Hartlaub, 1895; A. H. 

 Clark, 1912] (1, H.M.). 



Puerto Bueno, Smyth Channel; 30 meters or less; Capt. R. Paessler; October 25, 

 1893 [Ludwig, 1899; A. H. Clark, 1912] (1, H.M.). 



