226 DISCOVERY REPORTS 



and perhaps also to the young specimens from St. 167. On the whole it is scarcely pos- 

 sible to distinguish with certainty between Abatus cavernosiis and A. Philippii in the 

 young stages ; but when, as is often the case, only A. cavernosus is represented among the 

 adults from some station, the young ones occurring with them may no doubt be re- 

 garded as belonging to this species also. 



The specimen from St. 146, a young one 14 mm. in length, has the rostrate pedicel- 

 lariae remarkably diversified; its identification as A. cavernosus I must regard as quite 

 uncertain, though its globiferous pedicellariae are of the cavernosus type. It has two 

 subanal tube feet developed. The great depth, 728 m., is also unusual for cavernosus. 

 It is possible that it is really a new species of Abatus, but to base a new species of the 

 difficult genus Abatus on a single young specimen I would think unreasonable. 



Abatus cavernosus, var. bidens, Mortensen 

 (Plate III, fig. 10; Plate IX, figs. 9-1 1) 



Abatus cavernosus, var. bide?is, Mortensen, 1910. Swedish South Polar Exped. Echinoidea, 

 p. 73, pi. xix, figs. 32, 35, 39, 42. 

 St. 39. 25. iii. 26. East Cumberland Bay, South Georgia, 179-235 m. 2 specimens. 

 St. MS 15. 17. ii. 25. East Cumberland Bay, South Georgia, no m. i specimen. 



The information about A. elongatiis (Koehler) given below, p. 227, shows that the 

 present form has nothing to do with that species, as might be suggested. Perhaps it 

 would be more correct to regard this form as a separate species. 



Abatus curvidens, n.sp. 



(Plate III, fig. 9; Plate IX, figs. 17-20) 



St. 181. 12. iii. 27. Schollaert Channel, Palmer Archipelago, 160-335 ™- ^ specimen. 

 St. 182. 14. iii. 27. Schollaert Channel, Palmer Archipelago, 278-500 m. i specimen. 



Length Breadth Height 



mm. mm. mm. 



42 37 24 



36 34 23 



The larger specimen, which is the holotype, is a male, in a very good state of pre- 

 servation; the smaller specimen is a female, somewhat broken. 



Test low, but somewhat hemispherical, the apex being slightly anterior; it is dis- 

 tinctly broader in the anterior part, with a notch at the frontal ambulacrum, which is 

 only slightly sunken. The posterior petals are about two-thirds the length of the anterior 

 ones. Both of them are transformed into marsupia in the female. The peripetalous 

 fasciole is on the very edge of the test anteriorly ; some little distance behind the anterior 

 petals it bends sharply inwards ; the posterior part of the fasciole, across the posterior 

 interambulacrum, is nearly straight. The posterior edge of the test slopes slightly down- 

 wards. The labrum, which is rounded, extends backwards to opposite the middle of 

 the second adjoining ambulacral plates. The peristome not much sunken. Four well- 

 developed subanal tube feet. 



The globiferous pedicellariae are very numerous in the type specimen along all the 

 ambulacra inside the fasciole; a good number also occur on the posterior interam- 



