Bd VI: 4) THE ECHINOIDEA. 95 



The test (PI. XI Figs. 3, 5, 7, 8, 15, 18) is low, .is seen by the following mea- 

 surements: 



O* Length 38 mm. Breadth 36.5 mm. Height 22 mm. 

 $ » . 31 > » 29 » » 18 » 



The apical system is central or slightly anterior, somewhat sunken. The inter- 

 ambulacra form somewhat swollen ridges at the top; the sides are sloping gradually 

 towards the edge, which is broadly rounded . The outline of the test, with the spines 

 preserved (PI. XII Figs. 3, 5, 7), is oval, as seen from above; when denuded it is 

 seen to be somewhat truncated at both ends, even a little reenteringly curved at 

 the posterior end. The lower side is flat, only the actinal plastron is distinctly 

 elevated. 



The ambulacra agree with those of A. Lorioli in the feature of the anterior 

 ambulacrum being nearly as petaloid as the paired ambulacra, with the pores large 

 and arranged in a similar way. — In the male (PL XI Figs. 3, 7, 8) the ambulacra 

 are rather deeply sunken, especially the interporiferous part, the median suture lying 

 deepest. The petaloid part of the ambulacra is rather distinct from the non-petaloid 

 part, in spite of the lack of a fasciole. In the male there are in the anterior 

 paired petals 13 — 14 plates with large pores in each series (the inner, not yet fully 

 developed plates included), in the odd anterior and the posterior paired petals 12 — 

 13 plates with large pores in each series; all the petals are thus of nearly the same 

 length. From the 13th — 15th plate the pores are small and simple, and from there 

 the ambulacra, also the anterior, are flush with the test. The pores in each pair 

 are not widely separated, equally large, round; they are placed almost in the middle 

 of the plate, a little more outwards, the outer pore a little lower than the inner 

 one. The petaloid plates are naked in the inner part, set with miliary grains out- 

 side the pores; the non-petaloid plates are covered with irregularly placed large and 

 smaller tubercles in the same way as in the interambulacral plates. There is no 

 distinct series of larger tubercles along the edges of the anterior ambulacrum. The 

 non-petaloid part of the anterior ambulacrum is a little narrower than the petaloid 

 part, no widening occurring at the end of the petals as is the case in A.- Lorioli; 

 only in the posterior ambulacra there is a slight widening below the petaloid part. 

 The non-petaloid plates are slightly higher than the petaloid. On the actinal side 

 the ambulacral plates are almost naked, only with some scattered miliary tubercles. 

 — The female differs from the male in having the paired petals deepened and trans- 

 formed into marsupia (PI. XI Figs. 5, 15) as in Abatus; only 12 plates are included 

 in the deepened part. 



The interambulacra form rather swollen ridges between the petals, but the single 

 plates are not elevated in the middle. They are closely covered by uniform, rather 

 coarse tubercles, between which numerous miliary tubercles are found. On the 



