82 ECHINOIDEA. II. 



If we take these four groiips to represent genera, or at least snbgenera, which seems not at 

 all nnreasonable, the latter group must keep the name Ponrfalrsia. Of the names proposed bv Poniel 

 two become synonyms only of Potirtalcsia, viz. Phyalopsis (for laginujila) and Phyalc (for ffffn'xsi). 

 Only the name Crratophysa may be retained; P.rosea is named as the first species of this genus, but 

 the diagnosis is made from ccratopyga. The latter species must then be taken as the genotype. For 

 the two other groups I may propose the names: Helgocystis and Ec/ihiosigra. 



The old genus Ponrfalrsia is thus divided into four genera (or snbgenera), viz.: 



Helgocystis n. g. with the species cariiiata (A. Ag.). 



Echinosigra n. g. with the species pliialc (W. Th.) (genotype) and parailoxa (Mrtsn.). 

 Ceratophysa Pomel with the species ccratopyga (A. Ag.). 



Pourfalcsia A. Ag. with the species iiiiranda A. Ag. (genot\pe), laginiru/a A. Ag., Tai/ncri A. Ag., 

 Jcffrcysi W. Th., Wandcli Mrtsn. and hispida A. Ag. 



Perhaps the species Jcffrcysi, Waiidcli and hispida may yet prove to form a separate genus, 

 which would then get the name Phyalc Pomel.; for the present, however, it seems not necessarv to 

 separate these species from the genus Pourfalcsia. though it must be conceded that thev form a dis- 

 tinet group in that genus, differing from the other species in the shape of the test. P. Taiiucri. how- 

 ever, is in some way intermediate between the two groups (by its narrow anal snout). That it should 

 be necessary to make P. hispida the type of a separate genus there is no reason to suppose. 



Spatagocysfis Challciigcri A. Ag. has been ver}- carefully worked out, especially in the < Panamic 

 Deep-Sea Echini (p. 141), as regards the structure of the test. Three kinds of pedicellariæ have been 

 figured in the Challenger -Report (PI. XLII. 10—12 and XLV. 39—43), though — as is mostlv the 

 case in that work — not mentioned in the text I have found (on specimens examined in the British 

 Museum I two kinds of pedicellariæ, viz. tridentate and rostrate. Further I find in \\\\ preparation a 

 single globiferous and an ophicephalous pedicellaria resembling exacth' those of Urecliiiius Wyvillii. 

 As the specimens examined proceed from St. 147 from which station also Urcch. Wyvillii is recorded, 

 I think these ijedicellariæ do really belong to that .species, having only accidentally got between those 

 of Spatagocysfis. The tridentate pedicellariæ are richh- developed, occurring in at least two .different 

 forms, viz. one with simply leafshaped, more or less slender valves with the apophysis continuing into 

 the edge of the blade (PI. X. Fig. 20 represents a .small specimen of the slender form; larger specimens 

 are rather similar to those of Flcliinocrepis ciiiicata)., and another with rather short, broad valves, nar- 

 rowed in the lower part of the blade and terminatiug in a more or less prominent hook (PI. X. Fig. 10); 

 this is evidently the form figured in the Challenger -Report PI. XLII. 10 and PI. XLV. 39— 40 as a 

 «large-headed pedicellaria. I have not found so much meshwork in this as figured in the PI. XLV. 

 40 of the <Challenger»; there is often nothing at all. The form figured in PI. XLII. 12, evidently an- 

 other form of tridentate pedicellariæ, I have not seen. The rostrate pedicellariæ, figured as «short- 

 headed, toothed, cup-jDronged* pedicellariæ (PI. XLII. 11 and XLV. 41 and 43), are of a quite typical 

 form, with the outer edge of the rather short and broad blade provided with ca. 10—16 thick teeth 

 (PI. X. Fig. 18) ; the edge of the basal part is generally closely serrate, though not always so regularly 

 as in the specimen here figured. The stalk is more or less thornv (PI. X. F'ig. 35). — There is a vcrv 



