192 Bulletin American Museum of Natural History. [Vol. XXXII, 



Station 5694. Southwest of Santa Cruz Island, California, 640 fms. 



Station 5695. Southwest of Santa Rosa Island, California, 534 fms. 

 Bottom Temp., 38.9°. 



Station 5698. Off Monterey County, California, 475 fms. Bottom 

 Temp., 39.9°. 



Bathymetrical range, 525-640 fms. Temperature range, 39.9°-38.9°. 



Twenty-three specimens. 



Pseudarchaster pectinifer. 



Ludwig, 1905. Mem. M. C. Z., Vol 32, p. 106. 



It is only after the greatest hesitation that I call the largest Pseudar- 

 chaster in the collection by the name of the Panamic species. I certainly 

 should not do so if Fisher had not suggested the possibility that the northern 

 species dissonus intergrades with pectinifer. As the present specimen 

 entirely lacks the characteristic pedicellariae of dissonus and shows other, 

 slight differences, I cannot consider it that species. On the other hand 

 the adambulacral armature is utterly different from that of pectinifer as 

 described by Ludwig. But the latter only had a single specimen, much 

 smaller than mine, in which R = 140 mm., and perhaps with more material 

 the differences might sink into insignificance. In the specimen before me 

 the aboral portion of the margin of each adambulacral plate is much longer 

 than the adoral until near the tip of the arm ; or, in other words the angle 

 of each plate which projects into the furrow and separates adjoining tube- 

 feet is much nearer the oral end of the plate than it is the aboral. Ludwig 

 says the opposite condition occurs in pectinifer. In the present specimen, 

 there are only four or five furrow-spines on each plate, one on the adoral 

 side, one (the largest) on the point of the angle, and two or three on the 

 aboral side; on the actinal surface of the plate are eight to twelve somewhat 

 smaller spines, well-spaced and only indistinctly in rows. Ludwig says 

 there are eight or nine furrow spines and four to seven on the surface of the 

 plate. In my specimen there are eleven or twelve adambulacral plates to 

 ten inferomarginals, while Ludwig says that in pectinifer there are only 

 nine. — In view of these differences, I think it possible that the specimen 

 before me represents an undescribed species but more material must be 

 examined before the question can be settled. 



Station 5676. Off San Juanico, west coast of Lower California, 647 fms. 

 Bottom Temp., 39°. 



