CARBONIFEROUS BRACHIOPODA. 
31] 
42. Proddctus proboscideus, de Verneuil. Dav., Garb. Mon., p. 163, PI. XXXIII, 
figs. 1—4; Sup., PI. XXXVI, fig. 13. 
Since the publication of my description and figures of this species Mr. Joseph Wright 
has found a single but very fine example at Cruiscrath, Drogheda, in Ireland. Pro- 
diictus hermineus, an allied form, has also been found by the late Mr. T. Carrington, 
at Wetton, in Stafibrdshire. 
43. Productus aculeatus, Martin, sp. 
Dav., Garb. Mon., pp. 166 and 233, 
PI. XXXIII, figs. 16—18; Sup., PI 
XXXVI, fig. 10. 
Several paleeontologists are still of opinion that Productus Youngiamis should be con- 
sidered a mere variety or variation in form of Martin's species, and I will not assert that 
they may not be correct in the views they have expressed. Mr. J. Neilson writes me 
that he has some difficulty to determine where the one begins and the other ends, and 
that even from the typical locality of P. Youngiamis (Gorrieburn) specimens could be got 
showing the graduations between the two so-termed species. At p. 233 I gave Mr. 
Young's and Mr. Armstrong's opinions on the question. I have since then seen many 
specimens of Productus aculeatus measuring from half a line in length to nearly an inch 
in length, and in which no evidence of ribbing could be seen. At Dockra, Beith, 
Mr. Neilson has washed out of the Lower Limestone a great number of minute 
examples of the species under notice, and in forty-five examples, from the dimensions of 
half a line to three lines in length, the shell was almost smooth, with very few spines 
scattered over their surface, and showed no indication of the ribs which characterise P. 
Youngianus. From rotted Garboniferous Limestone at Gunningham Baidland, Dairy, 
Scotland, Mr. J. Smith, of Stobs, Kilwinning, obtained four examples of P. aculeatus, 
with their spines quite perfect, and rising at almost right angles from the plane of the 
shell ; the spines stood out erect on the lateral cardinal expansions, and acquired their 
greatest length on this portion of the ventral valve. I may also observe that in the 
Lower Garboniferous Limestone of Trearne, Beith, Mr. J. Young found innumerable 
examples of P. aculeatus, with all their spines attached ; some of their slender and 
delicate spines measured upwards of an inch in length. 
