262 Verrill, Notes on Radlata. 



have rounded but very prominent side-an<>les, so as to become nearly 

 heart-shaped ; lower arm-p!ates longer than broad, having a slight in- 

 curvature on the outer edge; upper arm-plates regularly ovul, not 

 much broader than long ; the disk has a diameter of 2'""' ; the slender 

 arms a length of c. 20'"™. Puntarenas, in 3 fathoms. 



The two preceding species and A. ndcrocUscus are very small species 

 allied to A. squamata M. and Tr., and all have the radial shields join- 

 ing each other completely ; mouth-shields lengthened, rhomboidal ; 

 outermost mouth-papilla broader than the other two ; lower arm-plates 

 pentagonal with an angle turned inward ; upper arm-plates trans- 

 versely oblong ; arm-spines three in number. 



Tw^o other species, A. Orstedii Liitk., from Puntarenas, and A. 

 margmata Ltitk. ( Ophiophnigmus rnarglnatus Lyman) from Realejo, 

 I have not seen. 



Hemipholis gracilis Vemii, sp. nov * 



A delicate species, closely allied to H. cordifera Lyman, with long, 

 slender arms ; arm-spines in three rows, tapering, thickened at base ; 

 mouth-shields broad pentagonal, with rounded corners ; under arm- 

 plates octagonal with rounded corners ; a single tentacle-scale. 



Arras about nine times as long as the diameter of disk. Mouth- 

 papilloe two to each mouth-slit, situated at the outer lateral edge, slen- 

 der, somewhat elongated, blunt. The mouth-slits, or spaces between 

 the jaws, are broad and regularly heart-shaped, the indentation in the 

 outer side formed by an acute, triangular projection from the inner 

 arm-plate, which is mostly concealed by the side mouth-shields, which 

 meet above it. The two inner tentacles are situated on each side of this 

 pointed inner angle of the first arm-plate, and within the mouth-slits. 

 Mouth-shields a little broader than long, somewhat pentagonal, the 

 outer edge nearly straight, the outer lateral edges short, the lateral 

 ano-les rounded, the inner lateral sides Ipnger, somewhat curved and 

 forming a rounded inner angle. Side mouth-shields elongated trans- 

 versely, meeting in front of the mouth-shields, and also across the 

 arms so as to form a continuous ring around the mouth ; the inner 

 side is concave, the outer has a central, projecting, acute angle, ex- 

 tending to the lateral angle of the mouth-shield. Under arm-plates 

 somewhat octagonal, broader than long, toward the base of the arms 

 the outer and inner edges are nearly straight, the lateral edges are 

 composed of three short sides, with rounded angles betAveen, wdiich 

 farther out on the arms become merged into a curved lateral line. 



* H. affinis Ljungraan, Ophiur. viventia, Ofv. af Kgl. Vet. Akad. Forh., May (?), 

 1867, p. 322, appears to be identical with tliis, — Reprint. 



