1496 THE VOYAGE OF H.M.S. CHALLENGER. 



stricted mouth. Cephalis with a stout pyramidal horn of the same length. Whole surface spiny. 

 Pores irregular, roundish. 



Dimensions. Length of the shell (with six joints) 0'22. Length of the single joints, a 0'02, 

 I 0-06, c 0-04, d 0-02, e 0'02,/0'06 ; breadth (in the third joint) Oil. 



Habitat. Central Pacific, Station 266, depth 2750 fathoms. 



Genus 648. Eusyringium, 1 Haeckel, 1881, Prodromus, p. 437. 



Definition. S tichocorida (vel Stichocyrtida eradiata aperta) with ovate or 

 spindle-shaped shell, the mouth of which is constricted, and prolonged into a terminal 

 cylindrical tube. Cephalis with a solid horn. 



The genus Eusyringium differs from the preceding closely allied genus Eucyrtidium 

 in the peculiar formation of the last shell-joint, representing a narrow, cylindrical, 

 fenestrated tube. It exhibits, therefore, to the latter the same relation as 

 Theosyringium bears to Theocorys. 



Subgenus 1. Eusyringartus, Haeckel. 



Definition. Shell with three strictures and four joints ; the third joint is the 

 largest, inflated, and much broader than the three others. 



1. Eusyringium conosiphon, n. sp. (PI. 78, fig. 10). 



Shell with four joints, very thick-walled, rough. Cephalis hemispherical, with a very stout, 

 smooth, three-sided pyramidal horn of the same length and breadth. Thorax hemispherical. 

 Third joint subspherical, three times as long, and twice as broad as the thorax, and of the same 

 length as the slender, inversely conical fourth joint. Pores in the three first joints subregular, 

 circular, in the fourth joint irregular. 



Dimensions. Length of the shell (with four joints) 0'25. Length of the single joint a 0'02, 

 I 0-03, c 01, d 01; breadth 012. 



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



2. Eusyringium pachy siphon, n. sp. (PI. 78, fig. 11). 



Shell with four joints, very thick-walled, rough. Cephalis conical, with a thick, dimpled, 

 conical horn of the same length. Thorax hemispherical. Third joint inflated, subspherical, and 

 fourth joint slender, inversely conical, as in the similar preceding species. Differs from the latter 



1 Eusyringium = Nice small tube ; if, o 



