ECHINOIDEA. II. 



63 



area of the Atlantic ( — its occurrence iu thu Bay of Bisca\' (Norman, op. cit.) niu.st likevvise be re- 

 garded as doubtful, tlie .statement evidenth- being- made withont a close examination of the speci- 

 mens — ), and I doubt that it will l)e found there. Poitrtalcsia fcffreysi is the only deep sea Echi- 

 noid known from the cold area; it is only known from there, and it will probably turn ont to inhabit 

 the cold area alone, as has been proved iox most of the animal forms of that region. From this consid- 

 eration Grieg (op. cit.) has already doubted the correctness of the identification of the specimens 

 from the American coast recorded by Professor Verrill under the name of Ponrfalrsia Jcffyrysi, and 

 the donbt was quite jnstified. 



22. Pourtalesia Wandeli Mrtsn. 



PI. V. Figs. 1—7, II — 12. PI. VIII. Figs. 1—3, 7. PI. XI. Figs. i, 13—14, i.S — 20, 23, 34—37, 40-41. 



Th. Mortensen: Sonie new species of Echinoidea. Vid. ^Nledd. Naturh. Foren. Kobenhavn 

 1905. p. 242. 



The shape of the test is rather elongated, more .slender than in P. Jcff'rrysi. The front end is 

 almost vertical; on the abactinal side the test rises gently towards the middle, where the greatest 

 height is found, and then slopes graduallv towards the ]:)osterior end. An abactinal keel is hardly 

 indicated in larger specimens, whereas it mav be more distinct in smaller ones. The test is not pro- 

 duced over the periproct; in side view the outline of the abactinal side is thus seeii to continue to 

 the posterior end of the short anal rostrum scarceh" without any sinuation over the periproct, a ver\- 

 conspicuous difference between the species and P. Jrff'revsi. as is seen on comparing the fignres 1 1 and 

 13, 18, 23 of PI. V, representing side views of the tests of these two species. — In \ounger specimens 

 the outline in profil of the posterior end is somewhat different (PL \'. Figs. 5, 12) in accordance with 

 the more developed abactinal keel, the periproctal sinuation being considerabl\- more distinct. The 

 sides of the test are almost parallel, the width augmenting onl\- very little towards the posterior half, 

 the greatest width being found a little past the middle; from there it rapidly narrows towards the 

 posterior end. The actinal side is almost flat — a conspicuous difference from P. Jrffrcysi. as is seen on 

 comparing the figures 11,12 and 13,18. PI. V. Among smaller specimens of the two .species this differ- 

 ence is, however, not so great, P. Jcffrcysi being flatter on the actinal side when yonnger. The 

 sternum and episternnm form a rather distinct actinal keel, which continues along the under side of 

 the anal snout. The actinal invagination is somewhat longer than in P. Jcffrcysi; the number of piates 

 in the odd ambulacruni is, however, the same as in Jcffrcysi, 12 — 13. The form of the peristome as in 

 Jeffreysi. — The test seems to me a little more fragile than in Jcffrcysi. 



Regarding the strncture of the test this species agrees in the main features with P. Jcffrcysi. 

 The labruni is generalh' not seen from without, may, however, be found as a small plate between the 

 ambulacrals I. a. i and V. b. i, which are distinctl\- developed; eiglit simple pores are found at the 

 posterior edge of the invagination (PI. VIII. Figs. 1,3); none of the inner ambulacral piates have two 

 pores. If the tube-feet are developed on all the piates I dåre not assert, as it is rather difficult to dis- 

 cern them among the small spines in this place, both spines, tube-feet and skin being covered by 

 dark violet pigment; also the pores may be very difficult to discern , as in P. Jcffrcysi. A small 

 plate may be found between the ambulacrals I and II ou one side and between IV and V on the 



