DESCRIPTIONS OF THE SPKCIKS. 275 



those of P. Paillettei (compare PL IV. figs. 8, 10, and PL XIV. fig. G), which lias 

 smaller and more numerous side plates, 

 P. Archiaci does not possess the elevated interradial processes of /'. Verneuili 



(l'l. XL fig. 5), and is thereby distinguished from it, apart from their differences in 

 other characters. The outline of the calyx generally, the form of the anal inter- 

 radius, and the characters of the ambulacra and hydrospire-slits separate it from 

 P.acuium (PL XIV. fig. 10). It is also unlike P. caryophyllatum (PL XIV. 

 figs. 1—4), but may be said to be a transitional form between this last and the two former 

 species. There appears to be a good deal of individual variation in the relative 

 length of the stem-like base of the calyx. The ornamentation of the basal plates is 

 quite similar to that of Pentremitidea Lusitanica (PI. IV. fig. 11), and might lead to a 

 confusion of the two species should the generic characters not be properly attended to. 



We have not been able to get a good view of the radio-deltoid sutures in any 

 example of P. Archiaci; but the rubbed-down summit which is represented on 

 PL XI. fig. 7 shows that the deltoids are really rather large plates, though much 

 overlapped by the radial limbs. The few aborted hydrospires of the anal interradius 

 (PI. XIV. fig. 5) are not seen in this figure. 



Localities and Horizon. Ferrones, Province of Asturias, Spain: Calcaire de 

 Ferrones, Lower Devonian. Colle, near Sabero, Province of Leon: Calcaire d'Arnao, 

 Lower Devonian (Presented by Dr. P. H. Carpenter, F.R.S.). 



PlLEXOSCHISMA NOBILE, E. & C. 



(PL XL figs. 1-4.) 

 Phcenoschisma nobile, E. & C, Ann. & Mag. Nat. Hist. 1883, vol. xi. p. 246. 

 Sp. Char. Calyx elongately ob-pyramidal, decreasing in width slowly, with sharp, 

 strong, and prominent interradial processes, truncated and terminating but little above 

 the level of the peristome ; section obscurely pentagonal. Basal plates forming an 

 obtusely conical cup. Radial plates very long and narrow, arched, the bodies and 

 limbs being about equal in length, and the former bluntly angular in the middle 

 line. The sinuses are exceedingly wide and deep, with high sloping sides, the edges 

 of which are prominent and a little thickened ; lips inconspicuous. Deltoid plates 

 large, forming the summits of the interradial processes ; anal deltoid truncated and 

 excavated at its distal end. Ambulacra narrow, linear, of uniform width through- 

 out ; lancet-plates at the bottom of the sinuses, entirely concealed by the side plates, 

 which are thirty or more in number, wedge-shaped in outline, horizontal in position 

 at the proximal ends of the ambulacra, and becoming arched downwards distaUy. 

 Outer side plates very small, placed at the extreme edges of the ambulacra, and 

 standing almost vertically so as to fill in the notches between the outer ends of the 

 side plates. Hydrospire-slits from twenty-five to thirty-five in number, occupying 

 the whole of the steep and subimbricate sides of the sinuses, closely crowded 



2n 2 



