CLARK : THE CIDARIDAE. 205 



spines whitish, longitudinally striated with deep reddish-purple ; on secondaries, 

 striations merge to form abroad stripe at tip of spine ; primary spines dull grayish, 

 sometimes indistinctly cross-banded with brown ; collar flesh-color or whitish. 

 Largest specimen 25 mm. h. d. ; vertical diameter, 13 mm. ; abactinal system, 12 mm.; 

 actinostome, 11 mm.; longest primary, 25 mm., a trifle more than 2 mm. thick at 

 base. 



That this species is closely related to panamensis seems clear, but that it is quite 

 distinct is certainly indicated by the available material. None of the specimens of 

 either are in any way intermediate. Both species were taken by the "Albatross" 

 at Station 337S, in 112 fathoms off Galera Point, Cape San Francisco, Ecuador, 

 but only panamensis was found near Cocos Island, and only dubia at Station 3397, 

 in 85 fathoms off Galera Point. Possibly dubia is a more southern species ; at 

 any rate, it is known only from the coast of Ecuador. 



Tretocidaris calacantha- 

 Dorocidaris calacantha A. Agassiz and Clark, 1907, Haw Pac. Ech. Cid., p. 11. 



Plates 13, 14, 34, 35, Haw. Pac. Ech. Cid., A. Agassiz and Clark, 1907. 



This very distinct species reaches a size of 43 mm. h. d., with spines 81 mm. long. 

 It is very pale brown with a greenish cast, especially on the abactinal system ; the 

 secondaries each have a broad green stripe ; the primaries are very faintly banded 

 with brown and at the base are finely spotted with white. This is one of the 

 species found by the " Albatross " at the Hawaiian Islands, where it is not rare 

 in 127-198 fths. 



Tretocidaris perplexa, sp. nov. 



Plate 6, figs 1 and 2 ; and Plate 7, figs. 1-4. 



Test somewhat flattened; vertical diameter, about .55 h. d. ; coronal plates 7 or 

 8; areolae small, only .60-.65 of horizontal length of plate, distinct and not very 

 deeply sunken ; median interambulacral area very fully covered with tubercles, 

 smallest next to vertical suture, which is quite distinct; ambulacra about one-third 

 of interambulacra in width; poriferous zones, broad and little sunken; median 

 ambulacral area with a double series of tubercles on each margin, inner much 

 smaller, and between these, 3-6 irregular series of small tubercles which sometimes, 

 but not always, conceal vertical suture; pores nearly horizontal, large, their hori- 

 zontal diameter much exceeding vertical. Abactinal system about .40 h. d., nearly 

 circular and clearly defined, flat and quite thickly covered with small secondary 

 spines ; genital plates rather large, nearly square or somewhat pentagonal, with 

 pores near outer edge ; ocular plates more or less triangular, with apex truncated, 

 when in contact with anal system, either wholly excluded, or some, or all except 

 right anterior one, in contact with a large anal plate ; anal system about one-half 

 of abactinal, with an external series of 10-12 large plates and 12-15 smaller ones at 

 centre; except along margins all plates of abactinal system covered with rather 

 coarse tubercles of nearly uniform size; each genital plate has 50-80 ± such tuber- 

 cles and each ocular 20-35 ±- Actinostome small, only about .35 h. d., not at all 



