WEST INDIAN STAKFISHES 



37 



The intermarginal plates are like the upper ones, but extend 

 regularly to near the small adoral area. Some of them some- 

 times bear two, or even three, conical spines, close together, but 

 ordinarily only one. The peractinal plates form a single row of 

 small, oblong, transverse connective ossicles between the infero- 

 marginals and the adambulacrals. Between them are large pap- 

 ular pores, either isolated or in small groups; many of these 

 ossicles are without spines, but some of them usually have a 

 small conical spine, near the outer adambulacrals. 



The adambulacral spines are small and subacute, in some- 

 what oblique transverse series of three. They are much smaller 

 and more numerous than the adjacent spines, about four of their 

 plates corresponding to one marginal plate. The inner furrow- 

 spine is much the smaller; the next is nearly as large as the 

 outer one. These last are webbed together basally and thus form 

 a contLQuous regular border to the furrow. Most of the dorsal 

 spines can be referred to five irregular rows, above the supero- 

 marginals. These are one pretty distinct median radial row, 

 and two less distinct dorso-lateral rows on each side. There are 

 also some irregular interpolated spines on the connective ossi- 

 cles. Many of the larger plates bear two and some three clus- 

 tered spines. 



The papular areas are large and the papulae are very numer- 

 ous, not only on the dorsal side, but also between the marginal 

 rows, and are present also next to the adambulacrals, where they 

 become less numerous. 



The madreporic plate is raised, flat, wart-like, covered with 

 rough projections, like stout spinules. 



The Young. Plate xxix; figure 2. 



A young specimen, apparently of this species, was taken by 

 the expedition in shallow water on the Great Bahama Bank. 

 Its radii are 7™™ and 26™™. It has the two rows of marginal spines 

 yrell developed and pretty regular. There are about eight or 

 nine in the upper series and about twelve in the lower. They 

 are relatively large, conical, acute. 



The dorsal spines are similar in size and form. They form, on 

 some of the rays, too pretty definite dorso-lateral rows of five 

 or six, with a few in the median row. In other cases the median 



