272 BULLETIN 82, UNITED STATES NATIONAL MUSEUM. 



of the pinnulars, which is roughened or studded with small projections on its 

 somewhat enlarged outer end, and near the border of the pinnular suddenly ex- 

 pands into a coarse meshed reticulation adjoining a similar reticulation from the 

 adjacent rods. 



There are no spicules in the tentacles. 



Leptometra celtica (figs. 795, 799, p. 372). — The lateral perisome of the pin- 

 nules is occupied by a continuous series of large plates, each of which distally over- 

 laps the base of the succeeding. The greatest diameter of these plates is in the mid- 

 dle ; the sides of the portion below the middle are strongly concave, curving about 

 the sacculi, the curve being sharpest about the outer border of the sacculi and 

 gradually straightening out toward the base of the plate; in the middle of the 

 outer border of the plate are two prominent narrow projections side by side 

 separated by a narrowly rounded or V-shaped notch. From the base of these pro- 

 jections the outer border forms a rounded obtuse angle which lies about halfway 

 between the bases of the processes and the middle of the distal and proximal sides, 

 where it abruptly passes over into the lateral conca\-ities. Usually on the distal 

 side the side of the distal outer process is carried further basally than on the 

 other, so that the angle on the distal outer border is much more nearly a right 

 angle than that on the proximal outer border; occasionally between the base of 

 the distal outer process and the angle on the outer distal border there is a rounded 

 notch, so that the latter takes the form of a prominent narrow angle directed out- 

 wardly; occasionally also the proximal side may run proximally from the tip of 

 the proximal outer process proximally and downward at an angle of 45° with 

 the edge of the pinnular to a point directly above the middle of the sacculus, when 

 it turns and runs perpendicularly downward. Viewed from the inside of the 

 plate the outer processes are seen to be much thickened; the thickening of the 

 distal process is confined to the process itself, while that of the proximal process 

 is continued for a considerable distance down on the inner face of the plate. The 

 outer third of the plate is curved inward toward the middle of the pinnule. 



The tentacles usuallj' contain a few small spicules which may form a group 

 or elongated patch in about their middle. 



Leptometra phalangiuvi. — Each ambulacral lappet typically contains a large 

 iind conspicuous covering plate which is triangular, higher than broad at the base, 

 with the inner border more or less concave; these are sometimes much reduced in 

 size and irregular in shape, and occasionally occur only as straight rods leaning 

 slightly distally; rarely a side plate is found beneath the covering plate. 



The tentacles usually contain a short band of roughened spicules near the 

 middle. Sometimes this band is narrower and much elongated; many of the 

 tentacles are entirely without deposits. 



Notocrinus virilis (figs. 1329, 1330, pi. 49).— The lateral perisome of the pin- 

 nules contains large plates which are usually triangular in shape with rounded 

 angles and mostly about half again as high as broad at the base. Their bases are 

 separated from each other by a space about equal, on the average, to half the basal 

 length. 



