CA ECHINOIDEA. II. 



onlv Olie, the left, is distinct in tlic fraomeiit preserved. B\ a ver\- careful preparation it will certaiiih' 

 l)e possible to make out fiilly the stiuctuie of the apical swsteni in this ver\- interesting form. 



As regards the pedicellariæ Calymne agrees with the Pourtalesiæ in ha\ing rostrate pedi- 

 cellariæ of the form common in that family. They are of two kinds (PI. X. Fig.s. 5, 6), one with the 

 outer end of the blade rather widened and finely serrate, the other with the outer edge onh httk- 

 widened and provided with few, rather large teeth. (This i.s, evidentl\-, the form figured in the Chal- 

 lenger -Echinoidea PL XLIII. 24 and XLIV. 47 as a Clypeastroid-like pedicellaria.) The stalk niay be 

 rather thorny, as is well shown in the Chall. -Ech. PI. XLIV. 48: probably it is the coar.se-toothed 

 form which has the thorny stalk, the other form having it smootli ; but I cannot say this with cer- 

 taintN'. The triph>-llons pedicellariæ are like those of Urech. iiarrsiainis. The miliary spines (PI. X. 

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

 edge; the shaft is verv slender, consisting of fine rods, whicii are not connected with transverse beam.s, 

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

 Evidently Calymne is not very closely related to the Urtcliiiiidæ ; I tliink it must form a separate 

 group (family), as it cannot be transferred to the Pourtaicsiiihr. the anterior ambulacrum not beiiig 

 in vaginated. (Comp. below p. 86. | 



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

 nungen , by Agassiz in the Preliminary Report ou the : Albatross -Echini, and by Doderlein in 

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

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

 Palæopneustes that I think Agassiz is quite right in referring it to the new faniih' Palæopneustid(r 

 established by hini (Panamic Deep-Sea Ech.), and I also think the establishment of tliat famih' 

 quite justified. 



20. Plexechinus hirsutus Mrtsn. 



PI. VI. Figs. S — 9, 12—16. PI. VII. Figs.9, 19-20. PI. X. Fig.s. 2. 15—1". '9. 2'. 23, 25, 27, 31—32, 34, 36— 3S. 



Th. .Mortensen: .Some new species of Echinoidea. Vid. Medd. Naturh. Forening. Kobenhavn. 

 1905. p. 242. 



The outline of the test is alinost regularly oval, especiall\- in the smaller specimens; in larger 

 specimens it is straight acro.ss the anterior ambulacrum or even slightly reenteriiigly curved. On the 

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

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

 abactinal side is beautifully rounded, except the posterior end, the odd interambulacrum not .sloping 

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

 011 the actinal side makes the posterior end much higher tlian the anterior. The anal snout is dis- 

 tinctly less prominent than in P. ciiictns, being scarcely discernible in dorsal view, a very conspicuous 

 difference from the latter species, as will be seen on comparing the figures 13, 14. PI. VI with PI. 58. 

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

 4_5 of the work quoted. — The wliole of the test (except the ambulacra of the biviuin ou the actinal 



