STROPHALOSIA. 48 



original representations published in 1839 and 1842, and finding these to belong to the 

 same species, it appears to me desirable, in order to obviate further confusion, to erase the 

 term excavata altogether ; and if the shell described as St. ecccavata by King (figs. 19 — 22 

 of my plate) is to be either viewed in the light of a separate species or variety of Goldfussi, 

 the term Lewisiana, De Koninck, is the one which should be adopted. So little is 

 known of the shell termed Strophalosia parva, King, 1 that I should not consider myself 

 justified in admitting it as a distinct or well made out species, and have therefore followed 

 Professor M'Coy and Mr. Howse in leaving it, provisionally, among the synonyms 

 of St. Goldfussi, which it appears to resemble; for the specimen in the Museum of 

 Practical Geology (fig. 18) proves that it was not always " irregularly circular marginally," 

 as stated by Professor King, since the individual before us is sub-trigonal, as is the case 

 with the larger number of St. Goldfussi. It has also been ascertained that the spines in 

 Minister's species very often attain the comparative length displayed in King's illustration, 

 as well as in the one I have represented. 



Far. Lewisiana, Be Ko?iinck. Plate III, figs. 19 — 22. 



Productus Lewisianus, De Koninck. Monographie du genre Productus, p. 150, 



pi. xv, fig. 5, 1846. 

 Orthotrix excavatus, part, Geinitz. Versteinerunger, pi. v, fig. 38 ; pi. vi, figs. 



20, 21, 1848. 

 Productus spiniferus, King. Catalogue of the Organic Remains of the Permian 



Rocks of Durham, &c, p. 8, 1848. 

 Strophalosia excavata, King. Monograph, pi. xii, figs. 13 — 17, 1850. 



Almost circular or slightly transversely oval marginally, and about as wide as long, 

 regularly concavo-convex : hinge-line shorter than the width of the shell, with a narrow 

 area in both valves, that of the larger one possessing a small fissure, covered by a pseudo- 

 deltidium. The ventral valve is generally uniformly convex, but in some examples presents 

 a narrow, very slightly marked, median depression on the anterior portion of the valve. 

 The beak is regularly rounded, incurved, and varying in its proportions : the smaller valve 

 is concave, following the curves of the opposite one. Externally the entire surface of the 

 valves is covered with a vast number of long, slender, tubular spines, which are situated 

 sometimes very uniformly in quincunx, but in the larger number of individuals this extreme 

 regularity does not appear to exist. The internal details are exactly similar to those of 

 the typical Goldfussi. In dimensions this variety does not in general exceed 10 lines in 

 length, by about the same in width. 



Professor De Koninck, Dr. Geinitz, and Professor King consider the shell under 



1 King's 'Monograph,' pi. xii, fig. 33, 1850. 



