964 THE VOYAGE OF H.M.S. CHALLENGER. 



on the outer and upper thorny. Apical horn and the three divergent feet nearly equal, straight, 

 about as long as the sagittal ring, with three thorny edges. 



Dimensions. — Height of the sagittal ring 01 to 012, breadth 0'07 to 0'09. 



Habited. — Central Pacific, Stations 270 to 274, dejjth 2350 to 2925 fathoms. 



2. Cortiniscus dipylaris, n. sp. (PI. 92, fig. 13). 



Sagittal ring nearly semicircular, with prominent distorted edges and six pairs of small 

 roundish piapillate tubercles (three pairs on the straight dorsal, three on the curved ventral rod). 

 Apical horn short and stout, with a tuberculate knob. Basal ring smaller than the sagittal ring 

 with two elliptical gates. Three feet short and stout, irregularly branched Kke a cauliflower, with 

 numerous short papillate tubercles. 



Di)nc7isions. — Height of the sagittal ring Oil, breadth 0'08. 



Habitat. — Central Pacific, Station 268, depth 2900 fathoms. 



3. Cortiniscus tripylcms, n. sp. 



Sagittal ring elHptical, smooth. Apical horn conical, smooth. Basal ring larger than the 

 sagittal ring, with three elKptical gates of equal size ; two paired, posterior (jugular pores) between 

 the basal parts of the caudal foot and the two pectoral feet), and an odd, anterior (sternal pore) 

 between the basal parts of the two pectoral feet and a connecting horizontal convex sternal bow. 



Dimensions. — Height of the sagittal ring 0"09, breadth 0"06. 



Habitat. — Tropical Atlantic, Station 348, depth 2450 fathoms. 



4. Cortiniscus tetrapylaris, n. sp. 



Sagittal ring elliptical, with four pairs of short branched thorns, two posterior on the straight 

 dorsal, and two anterior on the curved ventral rod. Basal ring smaller than the sagittal ring, with 

 four triangular gates ; the two anterior (jugular pores) a little smaller than the two posterior 

 (cardinal pores). Apical horn and the three divergent feet shorter than the sagittal ring, irregularly 

 branched, with curved, often tuberculate branches. 



Dimensions. — Height of the sagittal ring 0'08 to 0'012, breadth 0'06 to 01. 



Habitat. — Fossil in Barbados. 



5. Cortiniscus typicus, n. sp. (PI. 92, fig. 12). 



Sagittal ring ovate, thorny, with three distorted edges ; dorsal rod nearly straight and vertical 

 prolonged upwards into a stout thorny apical horn, downwards into the caudal foot. Basal ring 

 smaller than the sagittal ring, with four elliptical or nearly triangular gates ; the two anterior 

 (jugular pores) about half as large as the two posterior (cardinal pores). Three feet of equal size, 

 thorny, divergent, straight or slightly curved, about as long as the diameter of the sagittal ring. 



Dimensions. — Height of the sagittal ring 014 to 018, breadth 01 to 012. 



Habitat. — Cosmopolitan; Atlantic, Indian, Pacific, at various depths. 



