BCHINOIDEA. II. 147 



North Carolina to Bahia. The bathymetrical distribution is rather small, from shallow water to 85 

 fathoms. 



The specimens from the Kattegat are rather small, evidently the species reaches a more con- 

 siderable size at the Atlantic Coasts. Forbes (Op. cit.) thus mentions a specimen of 3 inches diameter, 

 and from the Biological Laboratory of Roscoff I have received specimens of a little over 6o mm length. 



The specimens from the Mediterranean differ from the northern specimens in the peculiar 

 feature that they alone appear to have globiferous pedicellarias, and even sometimes very richly de- 

 veloped. Further they have four ambulacral plates reaching within the subanal fasciole, whereas gene- 

 rally only three reach within the fasciole in the northern specimens. Otherwise I cannot see any reli- 

 able differences, so that I must regard them as belonging to the same species; at most the Mediter- 

 ranean form can be made a separate variety of Ech. cordatum. 



The American specimens were originally described as a distinct species, Ampkidetus Kurtzii 

 Girard, 1 which was later on by Agassiz («Revis. of Echini >) made a synonym of Ech. cordatum 

 After a careful comparison of a single specimen from the Coast of North Carolina with equal-sized 

 European specimens of cordatum, I must fully join Professor Agassiz in regarding the American form 

 as identical with the European Ech. cordatum. In all the more important structural features of the 

 test they are in complete accordance (in the specimen before me there are 2 pairs of pores within 

 the subanal fasciole, but the ninth ambulacral plate also reaches within the fasciole, so that specimens 

 with three pairs of pores within the fasciole will probably be met with). Regarding the shape of the 

 test the specimen in hand is a little broader than is generally the case in the European specimens, 

 and also the front end is perhaps a little more perpendicular; but it is, of course, impossible to judge 

 of the real value of these apparently trifling differences from a single specimen alone. It may be 

 remarked that the very few pedicellariae seen, viz. triphyllous, tridentate and rostrate (but no globi- 

 ferous) are also in accordance with those of the European specimens. 



Agassiz («Revision of Echini >. p. 350. PL. XIX. 10 — 15) describes and figures young stages of 

 this species of 6-3 — yg mm length. From the Kattegat I have specimens of all sizes from such as are 

 just metamorphosed and only o - 5 mm long. 2 Also the larva I have described from here 3; it occurs 

 in great numbers, making an essential portion of the Plankton in the months of June — July. No other 

 species of Echinocardium occurring in the inner parts of the Kattegat, the identification of the young 

 specimens is beyond doubt. I am thus able to give a rather full account of the postlarval development 

 of this species, wdiich may prove of some interest. Also the comparison with the development of Bris- 

 aster fragilis, described above p. in — 114, PI. XIII, is certainly not without interest. 



The youngest stages I find to agree very closely with those of Ech. flavescens figured by 

 Loven (On Pourtalesia. PI. XV). The development of the apical system follows much the same course 



1 Account of a new species of Spatangidae from the Atlantic Coast of the United States. Proc. Boston Soc Nat 

 Hist. 1S52. Vol. IV. p. 213. 



2 From 'Thor> St. 112. 1905 (56 33' Lat. N. i° 47' Long. E. 89 M.) there are immense numbers of quite young 

 Echinocardium. which quite agree with those of Ech. cordatum from the Kattegat. I do not, however, venture to decide, 

 whether they belong to Ech. cordatum or flavescens, both of these species occurring there. In none of them have pedicel- 

 larise appeared as yet. 



3 Die Echinodermenlarven der Plankton-Expedition. Ergebn. d. Plankton-Exp. d. Humboldt-Stiftung. Bd. II. J. 1898. 

 p. 102. Taf. IX. 5 — 11. 



19* 



