1915.] NATURAL SCIENCES OF PHILADELPHIA. ^ 79 



outside oral slits, large, provided with numerous scales. Arms very 

 short, very stout at base, higher than wide, rapidly tapering distally, 

 with acute tip. Dorsal and ventral arm 'plates well developed, 

 successive plates widely in contact with each other. Lateral arm 

 plates high, with numerous arm spines, often unequal and arranged 

 in two series. Tentacle pores large, with numerous scales. 



This genus includes Ophiura nodosa and stiiwitzii of Llitken, Ophio- 

 glypha elevata Lyman, 0. sculpta, sladeni (= Ophiura stiphra H. L. 

 Clark), and striata of Duncan, and 0. sterea and Ophiura brachyactis 

 of H. L. Clark, besides a new species, Stegophiura vivipara. 



The genotype is Ophiura nodosa Ltk. Stegophiura much resembles 

 a certain group of Amphiophiura, but differs in the shorter, stouter 

 and more rapidly tapering arms with more acute tips. 

 Stegophiura vivipara sp. nov. 



Diameter of disk 6 mm. Length of arms 13 mm. Width of 

 arms at base 1.5 mm. Disk pentagonal, or circular (especially 

 when the animal contains many embryos), convex, covered with 

 fifty to sixty plates on the dorsal side, including the radial shields. 

 Central plate pentagonal. Five pentagonal radials, directly surround- 

 ing the central plate, laterally overlapping each other. In each 

 interradial space of dorsal side is a large squarish plate, wider than 

 long, in contact with radial shields; latter irregular in outline, about 

 as wide as long, one overlapping the other, instead of apposed to 

 each other in radial line. On ventral side of disk plates rounded 

 and knob-like, with furrows between. Genital papillae blunt, close- 

 set, longer outwards and upwards, where they form small arm combs. 

 Oral shields pear-shaped, much longer than wide, wider without 

 than within, with acute inner angles and perfectly rounded distal 

 margins. Adoral shields large, meeting within along their whole 

 length. Five oral papillae on either wide, squarish, short, wide, 

 close-set; a pair of infradental papillae at apex of each jaw, much 

 longer and stouter than the other oral papillae, rather obtusely 

 pointed. Five teeth, very small, close-set, obtusely pointed. Arms 

 very short, stout at base, rapidly tapered distally. Dorsal arm 

 plates fan-shaped, about as wide as long, convex dorsally. Lateral 

 arm plates convex, those of the two sides separated both above and 

 below on the basal arm joints. First ventral arm plate large, tri- 

 angular, with obtuse inner angle and convex outer side, wider than 

 long; the following plates are octagonal, with very short proximo- 

 lateral and disto-lateral sides, the former concave at tentacle pores; 

 wider than long, wider without than within; from the six or seventh 



