ADDENDA ET CORRIGENDA. 



Porocidaris pnrpurata W. Th. Several specimens were takeii by tlie Thor: at 62° 57' Lat N. 

 19° 58' Long. W. 957 M. (off SoiTth Iceland) in 1903 and at 49° 25' Lat. N. 12° 20' Long. W. 1270— iiSoM. 

 (off Sonthwest Ireland) in 1905. — The Porocidaris clcgans mentioned by Koehler in Échinodennes 

 dn Candana (226. p. 89) is, as Professor Koehler kindly informs me, P. pnrpurata. 



In Part I. p. 173 I have established a var. Talisviani of this species, characterised by the 

 upper primary radioles having the neck swollen in a fnsiform manner and of a fine violet colonr. The 

 specimens taken by the »Ingolf have not the neck of the spines thns swollen, so that the specimens 

 from the «Talisman», which show that feature exceedingly developed mnst necessarily appear to me 

 at least a distinct variety. The additional material from the .Thor., however, shows that this variety 

 cannot be upheld. Among these specimens all transitions mav be found from such specimens with 

 the neck of the spines not at all swollen to such with the neck of most of the upper spines consider- 

 ably swollen, and this swollen j^art of the spines is of a beautiful violet colonr, which sometimes 

 continues almost to the point of the spines. The specimens upon which the var. lalisuiaiii was 

 established thus cannot be regarded as more than extraordiuary beautiful specimens of P. pnrpurata. 

 — For the rest the swelling of the spines has been sufficiently represented by Wyv. Thomson 

 (iPorcupine^-Echinoidea. PI. LX I. Figs. i, 4, 6) tliough he does not mention this peculiar feature in the 

 text. — It may be remarked that the neck is much louger in the upper spines than in those at the 

 ambitus and on the actinal side. 



Trctocidaris anintlata Mrtsn. The examination of some specimens of Tr. Bartlctti (A. Ag.) in 

 the U. S. National Museum has convinced me that Tr. aimnlata is only a synonym of the latter 

 species. The description of this species given in the <'.Blake»-Echiuoidea is so very insufficient that 

 it is scarcely possible to recognise the species thereby, and even the Fig. 16. PI. II of the Blake -Ech. 

 gives a quite wrong representation of the ambulacra. In the description ( Blake »-Echiuoidea. p. 10) it 

 is said: the poriferous zone is soruewhat flexuous, the furrows more distant, and the median ambu- 

 lacral granulation finer, than in the other West India species of the genus , and the figure shows the 

 ambulacra closely covered by tubercles, three on each plate, without any uaked space in the middle. 

 But the ambulacra of this species are really as I have described for Tr. anntdata (Part I. p. 17), each 

 plate bearing onl)' oue small tubercle at the lower edge, inside of the primary tubercle, leaving a 

 broad naked space along the median line. Only in the largest specimen (68"'"') is there in some of 

 the median ambulacral piates a third small tubercle inside the second tubercle, but still the naked 



Tlie Ingolf-Expi'dition. IV. 2. 22 



