458 BRITISH PALAZOZOIC FOSSILS. [ Bracnropopa. 
I have not quoted the Productus Geinitzanus of de Koninck as a synonym of this species, as Professor 
King recommends, because I think that species is clearly the young of Strophalosia horrescens, as Professor de 
Koninck himself suggests; nor have I, as the author of the Monograph of English Permian Fossils also suggests, 
quoted de Koninck’s P. Lewisi as a synonym, although it seems very closely allied, because I have not seen the 
distinct, narrow, mesial hollow in any of the English specimens ; but as Mr Lewis collected the type specimens 
at Humbleton, I have little doubt that that species must ultimately be merged into the present one. I find this 
species in Count Miinster’s collection from Gliicksbrunn under the very characteristic manuscript name Pro- 
ducta spinosissima, which well expresses the character which distinguishes the species from all others, namely, 
the very small size and great number of the spines. The more regular rounded form, broad, short rostral 
portion, and comparatively low cardinal area, separate this species well from the accompanying S. Goldfussi. 
Position and Locality —Common in the Permian magnesian limestone of Humbleton. 
LeptmNA (Strophalosia) Gotprusst (Miinst. Sp.) 
Ref. and Syn. = Spondylus Goldfussi Minster, Beitr. Vol. I. t. 4. f.3 = Productus Goldfussi de Koninck, Monog. 
Prod. t. 11. f. 4= Strophalosia Goldfussi King, Perm. Foss. t. 12. f. 1 to 12+ 8. parva id. id. f. 12. f. 33. 
Desc.—Receiving valve moderately convex, longitudinally ovato-trigonal ; greatest width near the front 
margin, gradually pointed towards the beak, which is large, obtusely pointed, projecting much beyond the hinge, 
but very slightly incurved, the cardinal area being about twice as high as wide, triangular, and very little curved; 
beak often inclined to one side; sides often unsymmetrical ; hinge-line much less than the width of the shell; a 
more or less distinct mesial furrow extending from the beak to the front margin. Entering valve slightly concave, 
leaving a considerable space for the animal. Surface of both valves with rather strong, small, irregular, concentric 
lines and waves of growth, and closely set with minute, subquincuncially arranged, round, or ovate spine-bases, 
usually three or four times their diameter apart, and nearly uniform in size on all parts of the shell (about five 
or six in two lines measured transversely), concentric imbrications strongest on the entering valve, spines when 
preserved, slender, crowded, interlacing, those of the receiving valve directed backwards towards the beak, and 
serving to attach the shell to foreign bodies, those of the entering valve converging towards a central point; 
interior of entering valve with a strong, prominent, rostral tooth, from which the mesial septum extends nearly 
half the length of the shell; at about half its length close on each side is a prominent, rather large, ovate hoss, 
from which the prominent edge of the large reniform impressions curve outwards and forwards on each side, 
returning with a sigmoid curve to the anterior extremity of the septum; pits for the cardinal teeth of the re- 
ceiving valve strongly marked. Length of average specimen eight lines, proportional length of entering valve *, 
greatest width =, depth of receiving valve ;3, depth of entering valve =. 
The form of this species is very variable and often unsymmetrical. The attenuated posterior end (from the 
length of the beak) distinguishes it easily from its allies. In some spots the spine-bases are more crowded than 
is indicated above. I observe small, much twisted tracks of a Permian Vioa in this shell not uncommonly. 
Position and Locality—Common in the Permian magnesian limestone of Humbleton. 
Genus. PRODUCTA (Sow.) See page 390. 
PropucTA ACULEATA (Mart. Sp.) 
Ref. and Syn. = Anomites aculeatus Martin, Pet. Derb. t. 37. f. 9 and 10 = Productus id. Sow. M. C. t. 68. f. 4 
= P. laxispina + P. spinulosa Phill. Geol. York. t. 7. f. 14. and t. 8. f. 13. (not of Sow.) 
Desc.—Receiving valve elongate, ovate, extremely gibbous, front and sides regularly tumid; beak very 
large, tumid, much incurved, projecting beyond the hinge-line ; hinge-line rather less than the width of the shell, 
forming very small, flat, easily broken, obtuse-angled, inconspicuous ears. Surface with delicate, thin, imbricating 
laminar lines of growth, at irregular distances ; surface covered with irregularly scattered, rather distant, pointed 
spine bases, which towards the margin of the older specimens give origin each to an obscurely marked, broad, 
