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



8. Coscinaspis isojwra, n. sji. (PI. 134, figs. 13, 14). 



Shell thick walled, with smooth surface, without crests and dimples. All pores of the shell 

 nearly of the same size and of similar form, about as broad as tlie bars between them, and about 

 two hundred in number, viz., fifty to sixty (regularly fifty-two or fifty-four) sutural pores and on& 

 liundred and forty to one hundred and fifty parmal pores (forty aspinal kidney-shaped pores, and one 

 hundred to one hundred and ten coronal circular pores : six in the angles of each equatorial plate, 

 and five in the angles of each tropical and polar plate ; if the disposition be quite regular, one 

 hundred and four or one hundred and eight). Eadial spines short, rudimentary, conical. 



Dimensions. — Diameter of the shell 0'2, of the pores and bars 0'012. 



Habitat. — Tropical Pacific, Station 218 (off Kew Guinea), surface. 



Subgenus 2. Coscinaapidium, Haeckel. 

 Definition. — Surface of the shell dimply, with a network of prominent crests. 



9. Coscinaspis ceriopora, n. sp. 



Shell thick-walled, with numerous (one hundred and sixty to two hundred ?) funnel-shaped 

 dimples, which are separated by prominent crests ; on the bottom of each dimple there is a simple or 

 double circular pore. If this species be quite regularly developed, it closely resembles the preceding, 

 differing from it mainly in the prominent combs of the surface. It resemldes also Ccriaspis favosa , 

 I'l. 138, fig. 6 ; but whilst in this latter the majority of the dimples are blind, here they are all per- 

 forated. The twenty aspinal dimples (in the centre of each plate) present at the bottom a coujale 

 of pores, all other dimples a single pore. Among the latter there are fifty to sixty sutural pores and 

 one hundred to one hundred and ten coronal pores, viz., six in each equatorial plate, and five in each 

 (if the other plates ; but the number is not quite constant. Eadial spines strong, in the inner part 

 cylindrical, in the outer conical. 



Dimensions. — Diameter of the shell 0'15, of the pores and bars O'Ol. 



Hahitat. — Tropical Pacific, Station 215, surface. 



Genus 357. Acontaspis,^ Haeckel, 1881, Proclromus, p. 4(58. 



Definition. — D o r a t a s p i d a with twenty plates, which are j)erforated by eighty 

 to two hundred or more parmal pores (in each plate two aspinal and tn'o to ten or more 

 coronal pores). Surface covered with by-spines. 



The genus Acontaspis has the same characteristic structure of the shell as Ceriaspis, 

 differing from it only in the presence of numerous by-spines. Each plate is perforated 

 by four to sixteen or more (commonly ten to twelve) parmal pores, the two central of 

 which are primary " aspinal pores," all the others being secondary " coronal pores." 



' .4co?itaspis=Sliield with spears ; anovriov, d.a-ri'(. 



