12 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I28 



with a wide, convex border set off by a lateral marginal furrow which 

 becomes shallower posteriorly, before joining the very deep posterior 

 marginal furrow which is an extension of the marginal furrow on the 

 posterior limbs of the cranidium. Genal spine short, rapidly tapered. 

 Surface covered with fine granules, among which are scattered larger 

 granules. 



Cranidia range in length from 2 to 7 mm. The smaller cranidia 

 are characterized by relatively shorter palpebral lobes, lesser diver- 

 gence of the anterior facial sutures, and lesser rearward expansion 

 of the anterior border. 



Remarks. — This species could briefly be descrijjed as differing from 

 Antagniiis gigas in being smaller and relatively narrower in all its 

 cranidial parts. It also has longer palpebral lobes and consequently 

 shorter (exsag.) posterior limbs. 



Occurrence. — The species, although uncommon, was recovered 

 from a number of boulders: B-i, G-i, G-16, G-17, G-41, and M-io; 

 one cranidium collected at Bic was found in the U.S.N.M. collections. 

 The type locality is boulder M-io, Metis. 



Ty/)^.?.— Holotype : U.S.N.M. No. 123856. Paratypes: U.S.N.M. 

 Nos. 123857-9. 



ANTAGMUS? LONGIFRONS Rasetti, new species 

 Plate 6, figures 12-15 



Available material. — Three well-preserved cranidia. 



Description. — Glabella well defined by the dorsal furrow, promi- 

 nent, tapered, with slightly concave sides, fairly rounded in front. 

 Four pairs of shallow glabellar furrows ; occipital furrow well im- 

 pressed, occipital ring rather short (sag.), bearing a node. Frontal 

 area well divided into preglabellar field and border by a marginal fur- 

 row which bends backward medially almost touching the dorsal fur- 

 row in front of the glabella. Border rather flat, tapering in width at 

 the sides. Palpebral area slightly convex and downsloping, 0.50 times 

 as wide as the glabella at its midpoint ; ocular ridges straight, rather 

 strongly oblique ; palpebral 0.30 times as long as the glabella, narrow, 

 somewhat elevated, defined by a distinct palpebral furrow, situated 

 slightly back of the level of the glabellar midpoint. Distance from 

 posterior end of palpebral lobe to posterior margin slightly greater 

 than length of palpebral lobe. Posterior limbs as wide (tr.) as the 

 occipital ring, rather slender ; distal portion somewhat longer than 

 proximal portion ; furrow fairly deep, reaching the distal end. An- 

 terior facial sutures slightly divergent in front of eyes, gradually curv- 



