^ ECHIXOIDKA. 11. 



only one, the left, is distinct in the fragment preserved. R\ a \er\- careful preiDaration it will certainly 

 be possible to make out fully the structure of the apical system in this \er>- interesting form. 



As regards the pedicellarise Calymine agrees with the Pourtalesiie in having rostrate pedi- 

 cellarise of the form common in that family. They are of two kinds (PL X. Figs. 5, 6), one with the 

 outer end of the blade rather widened and finel\- serrate, the other with the outer edge only little 

 widened and provided with few, rather large teeth. (This is, evidenth', the form figured in the Chal- 

 lenger; -Echinoidea PL XLIII. 24 and XLI\'. 47 as a Clypeastroid-like pedicellaria.) The stalk maybe 

 rather thorny, as is well shown in the Chall. -Ech. PL XLI\'. 48; probably it is the coarse-toothed 

 form w-hich has the thorny stalk, the other form ha\ing it smooth ; but I cannot say this with cer- 

 tainty. The triphyllous pedicellarise are like those of Urecli. narcsianus. The miliary spines (PL X. 

 Fig. 30) have the point widened so as to form a broad, fenestrated plate, finely serrate along the outer 

 edge; the shaft is very slender, consisting of fine rods, which are not connected with transverse beams, 

 except a few at the base. This form of spine also recalls those foimd in some Pourtalesise. — 

 Evidently Calymnc is not very closeh' related to the Urrchiiiida- : I think it must form a separate 

 group (family), as it cannot be transferred to the Potirtalesiidiv, the anterior ambulacrum not being 

 invaginated. (Comp. below p. 86.) 



The genus Phrissocystis is also referred to this famih- (by Meissner in Bronn. Classen u. Ord- 

 nungen , b}" Agassiz in the Preliminar\" Report on the Albatross -Echini, and by Doderlein in 

 Echinoidea d. deutschen Tief-See Exped.). This seems to be a rather unnatural place for this genus. 

 Unfortunately the structure of the plastron is not known, but so man\- other features point towards 

 Pal^opneiisfes that I think Agassiz is quite right in referring it to the new family Pal(Fopneiistid(F 

 established b\- him (Panamic Deep-Sea Ech.), and I also think the establishment of that famih- 

 quite justified. 



20. Plexechinus hirsutus ]\Irtsn. 



PI. VI. Figs. S— 9, 12 — 16. PI. VII. Figs. 9. 19-20. PI. X. I'igs. 2, 15—17, 19, 21, 23, 25, 27. 31—32, 34, 36— 38. 



Th. Morteusen: Some new species of E^chinoidea. Vid. Medd. Naturh. Forening. Kobenhavn. 

 ICK)5. p. 242. 



The outline of the test is almost regularly o\al, especiall\' in the smaller specimens; in larger 

 specimens it is straight across the anterior ambulacrum or even slightly reenteriugh- curved. On the 

 actinal side the anterior ambulacrum is a little sunken; the posterior interambulacrum forms a ver\- 

 prominent keel, prolonged into a Inroad, little projecting anal snout, surrounded by a fasciole. The 

 abactinal side is beantifulh rounded, except the posterior end, the odd interambulacrum nut sloping 

 at all but forming a rather prominent hood over the periproct. This feature together with the keel 

 on the actinal side makes the posterior cud uuicli higher than the anterior. The anal snout is dis- 

 tinctly less prominent than in P. cinchis, being scarcely discernible in dorsal \ iew, a very conspicuous 

 difference from the latter species, as will be seen on comj^aring the figures 13, 14. PL \T with PL 58. 

 Figs. 2— 3 of the Panamic Deep-Sea Echini , and the figures 12, 15 of the .same plate with PL 55. 

 4—5 of the work quoted. — The whole of the test (except the ambulacra of tlie Ijivium on the actinal 



