TRIBE MYTLIACEA. 253 
P. Muricata. Lam. 8.—Lin, Sys. 1160?—D. p. 328.—Knorr. 
6. ¢..20.f. 1.—W. t. 12. f. 9.—Ch. f. 781. badly.— List. t. 370. f. 
210. Thin, pellucid, pale fulvous, subtruncated, the longitudinal 
sulci few and muricated: the scales small erect and somewhat 
acute; posterior side unarmed. Atlantic, Antilles. Moderately 
large. 
P. Pectinata* Lam. 9.—D. p. 325.—Lin. 1160 ?—Turt. Biv. 
t.19. f. 1.—W, t. 12. f.4.—Phil. p, 74.—Gualt. t. 79. A.— Mont. 
p.178. Triangular-oblong, horncoloured, with numerous radiating 
elevated narrow sulci(except on the ventral side which is merely 
roughened by the crowded layers of growth) which are often armed 
with very small distant concave scales; dorsal edge straight, the 
longer, angulated at the subtruncated anterior base; ventral edge 
elongated, incurved towards the beaks, elsewhere nearly straight. 
7. N. Europe. The specimen in Linnzus’s collection much more 
resembles Inflatus than this our British Species. 
P. Saccata. Lin. 1160.—D. p. 333. (partly) —Lam. 10.— Leach 
Z. M.1. t. 51.—Rump. t. 46. f. N.--P. Nurratu. Con. J.A.N.S. 
Phil.7.t. 19 f. 4. Satchel shaped, subquadrate, smooth: thin, 
horn coloured, the disk with about five prominent broad undulating 
unarmed ribs ; posterior ventral edge incurved, anterior base sub- 
truncated. 8.—Amboyna, Se.! 
P. Varicosa Lam. 11.— Seba. 3. t. 92. (the two penult side f.) 
Semitransparent, not spinous, reddish rufous, obliquely rounded 
at the anterior ventral margin ;_ with thick waved varicose radiating 
ribs : a cloudy blackish brown spot towards the base of its poste- 
rior side. 8.—Isle of Trinity. M. Deshayes remarks “Should the 
ewistence of this species, depend on the authority of Scba’s figures, the 
species must be expunged, as Seba has represented a variety of 
Rudis.” 
P. Bicotor. Chem. f. 780. (distorted)—W. t. 13. f. 14. (copy of 
Ch.)—D. p. 330.—P. Dorasrata. Lam. 12. Moderately ventri- 
cose, elongated, imbricated and lamellar near the anterior ventral 
margin which is obliquely rounded, with obsolete longitudinal sulci ; 
greyish rayed with smoky brown, semitransparent ; anterior margin 
very long, straight and subacute. South Seas. 14.—Australia. 
P. Incens* Pen. 4. p. 115.—WMort. p. 180. and Sup. p. 72.— 
Lam.13.—D. p. 325.—Turt. D. p. 148.—P. Incens anv Fraeiuis 
Turt. B. p. 222. t. 20. f.1,2.—P. Lzvis. Don. t. 152. Ovate- 
triangular, moderately long, more or less rugged, with very narrow 
distant unarmed (except when very young) radiating ribs which be- 

' We have given a copy also of Chemnitz’s Saccata W. ¢. 13. /f. 
18. which is undoubtedly distinct from this and more like Conrad’s 
Semicostata. 
