158 REPORT OF NEW JERSEY STATE MUSEUM. 



pointed. No longitudinal furrow, hardly even a depression. 

 Internally articular ridge very prominent in upper part, and 

 variable crest for tergal depressors well developed. Internal 

 carinal edge of each compartment from sheath to basis usually 

 projects little inwards beyond general internal surface of shell. 

 Basal edge of projecting margin rests on calcareous basis and 

 crenated like basal edges of longitudinal parietal septa. Whole 

 internal surface of shell ribbed, but ribs not very prominent. 

 Parietal tubes large, crossed in upper part and often low down 

 by thin transverse septa. Longitudinal parietal septa only 

 slightly denticulated at bases, and occasionally dividing at basis 

 close to outer lamina of parietes, making some short outer sub- 

 ordinate pores. In circular furrow below lower edge of sheath 

 sometimes little ridges dividing into small cells, though some- 

 times this furrow filled up by irregular knobs of calcareous 

 matter. Radii always rather narrow, often form mere linear 

 ribbons of nearly uniform width along edges of compartments. 

 Summits or edges always more or less irregular and jagged. 

 Their septa fine, barely or not at all denticulated. Alae with ob- 

 lique summits, sutural edges rather thick and distinctly crenated. 

 Basis flat, calcareous, very thin, surface slightly marked by radi- 

 ating furrows corresponding to radiating pores in bases of most 

 species. 



Labrum of mouth with six teeth. Mandibles with fourth 

 tooth minute or rudimentary, and fifth generally confluent 

 with inferior angle. Maxillae usually with small notch un- 

 der upper pair of great spines. First pair of cirri with rami 

 very unequal in length, one ramus nearly twice length of other. 

 Segments in two rami of first cirrus ten to twenty-three, or eight 

 to thirteen. Second cirrus with only two or three more segments 

 than shorter ramus of first pair. Third cirrus with one or two 

 more segments than second though decidedly longer. On dorsal 

 surfaces of both segments of pedicel of third cirrus tuft of fine 

 spines. Segments of these three pairs of cirri not much pro- 

 tuberant in front. Segments of posterior cirri have each four, 

 or five, or six pairs of spines. Basal diameter three-quarters of 

 an inch, 1.6 inches in distorted individual. (Darwin.) 



