Davidson — On Synngothyns. 315 



and for whicli omission I gladly apologise ; but at the same time it is 

 also right to add that as early as 1841 both Mr. Bouchard and myself 

 were well acquainted with the internal characters of the ventral 

 valve of this species, as well as of C. Demarlii, for we had found 

 specimens showing the position of the septum and dental plates in 

 an excellent state of preservation in the Devonian quarries of 

 Perques in the Boulonnais, and it was from those specimens that the 

 figures given in my Monograph were drawn. I was not, conse- 

 quently, indebted to Professor King for the information I possessed 

 upon this subject; but am exceedingly glad to learn that he has dis- 

 covered vestiges of spiral coils in Cyrtina Jieteroclita, as I had not 

 hitherto been so fortunate as to see them in any of the many specimens 

 of the species I had obtained. I may also here repeat that I still 

 adhere to the opinion expressed in my Monograph, namely, that, un- 

 til sufficient proof to the contrary can be adduced, I must continue 

 to consider G. carhonaria and C. septosa, as referable to the same 

 group as that typified by C. heteroclita and C. Demarlii, and that they 

 apparently all possess a perforated shell-structure. 



EXPLANATION OF PLATE XIV. 



Figs. 1-5. Syringothyris typa, from drawings communicated by Professor Winchell. 

 1. Dorsal valve (cast). 2. d. dorsal, v. ventral valves, I. line in- 

 dicating the length and position of the dental plates. 3. Dorsal and 

 part of the ventral valve seen in profile. 4. Beak of ventral valve 

 partly destroyed ; a. area, I. dental plates or lamellse, t. tube in- 

 complete, r. mesial ridge. 5. Section through a.b. The same 

 letters refer to same parts. 



Figs. 6-9, Syringothyris ? distans, Sow., from the Carboniferous limestone of Vise, in 

 Belgium. 6. Part of the beak of ventral valve, seen from the 

 back, and after Professor L. de Koninck's original figure, published 

 in 1859, 7, 8, 9. My drawings from the same specimen, enlarged. 

 7. Area and pesudo-deltidium. 8. The same viewed from the 

 opposite side, the shell forming the back of the ventral valve 

 being removed so as to show the shape and position of the dental 

 plates, as well as the position of the transverse plate and tube. 9. 

 The same seen in front; the area and pesudo-deltidium being 

 foreshortened. 



Fig. 10. Syringothyris cuspidaia^ or typa ? from Millecent, Ireland. 



Fig. 11. „ ,, from same locality. A transverse section of the 



beak having been cut through by Dr. Carpenter to show the 

 position of the dental plates, transverse plate, and incomplete tube, 

 as seen in the American specimens of Syringothyris typa. In this 

 specimen portions of the shell were perforated, while other parts 

 were free. Indications of the spiral coils may here also be 

 perceived. 



nsroTiOEs oif D^vd:E3V[:oII^s. 



I. — On the Punctate Shell- structure of Strtngothtris. By 

 P. B. Meek, (from Silliman's American Journal of Science and Arts, 

 May, 1867, p. 407). 



HAVING recently examined Professor Winchell's types of his genus 

 Syringothyris, which he was so kind as to loan me, I find them all, 

 with the exception of two silicified specimens (showing no structure). 

 distinctly punctate. It is probable that Professor Winchell had hap- 



