1046 THE VOYAGE OF H.M.S. CHALLENGER. 



jugular pores ; above the latter (on the frontal face) two large mental pores. Two pectoral feet 

 large, half as long as the shell, at the base fenestrated, vertical, and parallel. Two sagittal feet 

 much smaller, nearly horizontal, pyramidal (the caudal larger than the sternal foot). Two 

 longitudinal pectoral ribs arise on the frontal face. 



Dimensions. — Shell 0-21 long, 014 broad ; lateral feet 01, sagittal feet 0-02. 



Habitat. — South Atlantic, Station 332, depth 2200 fathoms. 



2. Tessarospyris nucifofmis, n. sp. 



Shell nut-shaped, papillate, with deep sagittal stricture. Pores irregular roundish, on both sides 

 of the ring three to six times as large as on the lateral sides. Basal plate with four large pores. Two 

 pectoral feet cylindrical curved, twice as long as the shell and as the two sagittal feet ; the caudal 

 is much stronger than the sternal foot. 



Dinwnsions. — Shell 0-06 long, 0-09 broad ; lateral feet 01, sagittal feet 0-05 long. 



Halitat. — Tropical Atlantic, Station 347, depth 2250 fathoms. 



3. Tessarospyris seminulum, Haeckel. 



Petalospyris seminulum, Stbhr, 1880, Palaeontogr., vol. xxvi. pL iii. fig. 12. 



Shell subspherical, smooth, with shght sagittal stricture and small circular pores ; some larger 

 pores on both sides of the ring. Basal plate with two large (lateral) pores only. Four feet nearly 

 equal, short, conical, divergent, scarcely one-fourth as long as the shell. 



Dimensions. — Shell 0'06 long, 0'08 broad; feet 0'016 long. 



Habitat. — Fossil in Tertiary rocks of Sicily (Grotte), Stohr. 



Subfamily 4. Hexaspyrida, Haeckel. 



Definition. — Zygospyrida hexapoda, with six descending basal feet; three of 

 these are primary (one odd caudal and two paired pectoral feet), the other three are 

 secondary, opposed diametrically to the former and alternating with them (one odd 

 sternal and two paired tergal feet). 



Genus 453. Hexaspyris,^ n. gen. 



Definition. — Zygospyrida with six basal feet and one apical horn. 



The genus Hexaspyris and the two following closely allied genera represent 

 together the peculiar subfamdy of Hexaspyrida, and differ from the other Zygospyrida 

 in the possession of six descending basal feet; three of these are the three original, 

 perradial, or primary basal feet of Cortina, Cortiniscus, Plagoniscus, Plectaniscus, 

 Triposp>yris, &c. ; the other three, usually opposed to the former diameti'ically, are 



' ifea;asp2/rw= Basket with sLx feet ; tia, oxpj/j. 



