268 DISCOVERY REPORTS 



three instead of five major suboral spines. The single series is continued from middle 

 to outer end of plate by 5 smaller spinelets, or 3 spinelets and the pedicellaria just 

 mentioned. 



Type locality. St. 272. Off Elephant Bay, Angola, 73-91 m., i specimen. 



Specimens examined. The type and 2 from St. 279, off Cape Lopez, French Congo, 

 58-67 m. 



Remarks. This species seems to be definitely in the ciliaris group on account of the 

 superomarginal plates abruptly larger than the adjacent lateral paxillae and the squarish 

 block-like inferomarginals. The regular alternation of 2 and 3 long lateral spines is 

 highly characteristic. The mouth-plates, however, are very convex and the presence of 2 

 pedicellariae near the inner end, deep in furrow, is similar to the condition in L. avicidaria 

 (subgenus Integraster Doderlein, 1920, p. 243, fig. 19). 



This species is related to L. aciculata Mortensen but not closely to any other in the 

 ciliaris group. 



Luidia aciculata Mortensen 

 (Fig. M, 5) 

 Luidia aciculata Mortensen, Echinoderms of St Helena, 1933, p. 425, text-fig. 7, pi. 20, figs. 7-12. 

 St. 279. Off Cape Lopez, French Congo, 58-67 m., i specimen. 



This specimen was dredged along with the two smaller examples of L. Jieterosona, and 

 is not fully grown since the dimensions are R 45 mm., r 6 mm., br 7 mm. The longest 

 arm fragment of type is 130 mm. and the broadest, 12 mm. The specimen agrees in most 

 details with Mortensen 's description and line figures. The paxillae, devoid of pedicel- 

 lariae, all have the enlarged central spinelet. There are i or 2 conspicuous, conical tri- 

 valved actinal intermediate pedicellariae. The mouth-plates have 2 spinelets at inner 

 end, close to nerve ring, co-ordinated into a simple pedicellaria; there is a very slender 

 spinelet adoral to the outer and smallest of the 3 adambulacral spines ; the actinal plates 

 bear a group of usually 3 spinelets. 



Mortensen 's description reads: " Inferomarginals with 3, in the proximal part some 

 of them with 4 large, erect, cylindrical, pointed spines, the uppermost the longest." In 

 the Discovery specimen the first plate is very compressed with 3 smallish ventral spines, 

 the lowest the largest ; second plate with 4 larger spines, the upper very much larger, 

 and equal to the succeeding ones ; third plate, 3 spines, the upper normal, the 2 lower 

 larger than the 3 of second plate. From here on there are 2 large spines on each plate ; 

 but on alternate plates the pair has moved downward so that the dorsal spine is removed 

 from upper end of plate and stands out of line, as does the lower with the corresponding 

 spine of adjacent plates, precisely as in the diplacanthid plates of the 2 specimens of L. 

 heterozona from St. 279. 



This difl^erence in the position of spines may be accentuated in young specimens and 

 therefore may have escaped notice in larger examples. The peculiarity points to a closer 

 relationship between aciculata and heterozona than between either of these species and 

 any other in the ciliaris group. Even the mouth-plates with the furrow pedicellaria are 



