ABATUS PHILIPPII. 175 



four old ones which had been straightened out by Mortensen, but I cannot 

 avoid the feeling that my honored French colleague allows little room for indi- 

 vidual diversity. 



Key to the Species of Abatus. 



Modified or sunken portion of paired petals begins close to abactinal system. 

 Width of test .85 of length or usually much more. 



3-6 pairs of tube-feet near periproct enlarged, penicillate; petals II and IV 

 diverging from long axis of test by an angle of only 45°-50°. 



Petals I and V as wide as II and IV; in female all 4 are deeply sunken . . cavernosus. 

 Petals I and V are distinctly narrower than II and IV, only the latter 



sunken in female philippii. 



Tube-feet near periproct not enlarged or 1, 2 and rarely 3 pairs may be; petals 

 II and IV diverging from long axis of test by an angle of 60°-70°. 



Ambulacrum III deeply sunken dorsally; anterior margin of test corre- 

 spondingly notched; petals about equal cordatus. 



Ambulacrum III not sunken; anterior margin of test not notched; petals I 

 and V may be longer than II and IV. 



Apical system central; peripetalous fasciole, especially anteriorly, 



not near ambitus agassizii. 



Apical system anterior; peripetalous fasciole, especially anteriorly 



approaches nearly or quite to ambitus shackletoni. 



Width of test only .80 of length koehleri. 



Modified or sunken portion of paired petals begins only some 8 or 9 pore-pairs distant 

 from abactinal system nimrodi. 



Abatus cavernosus. 



Schizaster (Tripylus) cavernosus Philippi, 1845. Arch. f. Naturg., 11, 1, p. 345. 

 Tripylus (Abatus) cavernosus Troschel, 1851. Arch. f. Naturg., 17, 1, p. 72. 

 Abatus cavernosus LoveX 1883. On Pourtalesia, p. 25. 



This is the characteristic species of the southern part of South America 

 and of the neighboring islands. It is known from South Georgia and Juan 

 Fernandez and probably occurs at the Falkland Islands also. There are speci- 

 mens in the M. C. Z. from as far north as Cape Corrientes and "off La Plata." 

 The types of Spatagodesma diomedeae are very young specimens of this species, 

 as Mortensen has suggested. 



Abatus philippii. 



Lov6n, 1871. Ofv. Vet. Akad. Forh., no. 8, p. 6, fig. (desc. impar). 

 Mortensen, 1910. Swedish South Polar Exp. Ech., p. 83 



Lov6n's account of this species is totally inadequate and only Mortensen's 

 work justifies the use of the name. Moreover it is quite possible that this so- 



