94 PERMIAN FOSSILS. 
Perhaps the development of deltidial spmes may only be a feature in those Strophalosias 
with a large area, like that of Aulosteges Wangenheim. Strophalosia Goldfussi has a 
large area; and its deltidium, as already noticed, possesses obscure indications of 
irregular rismgs : perhaps the latter are rudimentary deltidial spmes? It will thus be 
seen, if Aulosteges possess no other distinctive character than the one just noticed, tha 
I am little disposed to regard it as distinct from Strophalosia. 
With respect to Dr. Geinitz’s genus Orthothriz, it is obviously the same as 
Strophalosia, the name of which claims adoption on account of its having nearly two 
years priority of publication. 
Dr. de Koninck, in his ‘Monographie du Genre Productus,’ objects to the genus 
Strophalosia on some very insufficient grounds ;' but it is singular that this gentleman, 
in describing his Productus Buchianus, overlooked the area and teeth, which I readily 
discovered on some specimens in the collection of Mr. T. Davidson. There is no 
doubt on my mind of this sheil being a true Strophalosia, a view completely proved by 
the form of its reniform impressions. 
I may here advert to the interesting shell figured by Mr. J. de C. Sowerby in the 
‘Mineral Conchology,’ pl. 615, fig. 1644, under the name of Leptena anomala. Mr. 
Sowerby having very kindly permitted me to make an examination of the original of 
these figures, I have been able to satisfy myself that it does not belong to Leplena, 
at least, limited as this genus must be, to forms represented by its type, the L. rugosa 
of Dalman. Although I closely examined the specimen, I regret, from not being able 
to observe any teeth, my inability to speak with certainty as to the genus in which it 
ought to be placed. In its area and deltidium this shell corresponds with the genus 
under consideration; but until something is known of its internal characters, I feel 
reluctant to make any more than this passing allusion to the agreement. 
I was formerly somewhat of the opinion that Strophalosia differed from Productus 
in having both valves furnished with spines ;’ but their occurrence on the same valve 
of Productus horridus (vide ante, p. 90), P. punctatus,’ and some others, shows that I 
was premature in this respect. 
Perhaps what has just been noticed ought to induce some caution in repeating what 
I formerly stated respecting there being “a slight but interesting difference between 
1 If the so-called Productus punctatus, with an area and a fissure, figured by Dr. de Koninck (Mon., 
pl. xii, fig. 26), as showing the futility of any genus founded on these characters, is really of the species 
named, the argument amounts to nothing, as it is founded on merely an abnormal form. 
2 Vide Annals and Magazine of Natural History, vol. xviii, p. 28. 
* M. de Verneuil notices the presence of points (petites piqures) on the flat valve of this species when ~ 
slightly deprived of a portion of its shell (vide Geol. Rus., vol. , p. 777). I have a specimen exhibiting 
the same valve furnished with spines as long and as crowded as they are on the large valve represented in 
the work quoted, at figure 3, plate xvi. : 
* Productus spinulosus (vide Min. Conch., pl. Ixviii, fig. 3) is stated to have its small valve furnished 
with spines. 
