OF THE SPECIES. 83 



as general, it belongs especially to the upper and middle Silurian strata {Ludlow, Dudley, IVenlock). 

 In Sweden it is only found in the limestone of Gothland, which is wanting in Esthonia. In Germany 

 it seems to occur in only travelled fragments, and appears to have been transported from the Scandi- 

 navian mountains. Torrubia found it in Spain, on the frontier of Pardos, two leagues from Molina 

 de Arragon. In North America it is found in difl'erent places, especially near Lebanon, in the state 

 of Ohio, and at Trenton Falls, in New York. JSIurchison also mentions specimens from the Cedar 

 Mountain at the Cape of Good Hope. 



4. C. caHlcephata : Limbo scuti cephalici incrassato, oculis altis extemis, marginem superantibus ; 

 tuberculo capitis utrinque trUobo : lobis posticum versus majoribus. Long. 2}i. Table II, Figs. 9-10. 



Be/. — Green, Mon. 30. Milne Edw. C'rmi. iii, 319. 2. 



More nearly allied to tlie preceding species in habit, but the cephalic shield is com- 

 paratively shorter and broader, the sides more strongly curved, the posterior angles more 

 turned backwards. The reflexed margin is not very strong, at least not at the anterior 

 part, where it is usually highest. The eyes are rather small, but are remarkably prominent, 

 so that they project from above over the external margin of the shield ; they are situated 

 at the anterior part beside the front lobe of the glabella. This lobe is small and very 

 narrow ; the second certainly less broad, but projecting more outwards ; the third is 

 remarkably broad, large, semicircular, and separated for the greater part not only from the 

 preceding lobe, but also from the axis of the head by a furrow (as in Cal. Trisfani). I have 

 not seen the body and tail ; according to Green, the two together consist of fourteen rings, 

 in which case only one would belong to the tail ; the axis of the latter is almost of equal 

 breadth, therefore very obtuse at the posterior part, and the lateral lobes are not furcated. 



Loc. — Ixi North America, it occurs in Hampshire, Virginia; on the shores of the 

 Miamis, at Cincinnati ; and in Indiana ; in a blackish gray limestone. This species is not found 

 at Trenton Falls, where Cal. Blumeiihacliii is so frequent. I saw a plaster cast of the head 

 (No 2, Green) in the Berlin Natural History Cabinet. 



Remarks. — The other species, considered as belonging to Calymene, are arranged by me under 

 other groups. 



1. Cal. bellahda. Dalm., and Cal. concMm«, Dalm., are the representatives of two particular genera; 

 C. actinura. has been already mentioned (p. 69) and C. sclerops is a Phacops. Of C. punctata, I know 

 only the caudal shield ; it forms according to Boeck (Gaea Norweg. 13) a particular genus, including 

 also Cal. variolaris. 



2. 1 can give the following explanations respecting Green's various species : oi C. selenecephala 

 (p. 31 ; Milne Edw. 320, 3 ; Emmr. Diss. 40, fi) I have seen a plaster cast (No 3 of Green), but 

 owing to the badly preserved state of the specimen from which it had been taken, I could not arrive at 

 any sure specific characters. C. microps, Green (p. 34, Model 6), is a Phacops, and will be alluded to 

 more particularly under this genus. C. anchiops (p. 35, Model 7) likewise belongs to the genus 

 Phacops, but not C. diops, which forms a separate genus with Cal. concinna, Dalm. C. macrophthahna 

 (p. 89) is a Phacops, and C. Bu/o (p. 41) likewise. C. odontocephala (Gr. Suppl. p. 9, Milne Edw. 

 322, 8) is likewise a Phacops, but a distinct species. 



3. Murchison's Calym. Downinigice [Sil. Syst. ii, 655, PI. XIV, Fig 3) and Cal. tuberculata (A c. 

 Fig. 4) belong to Phacops ; his Fig. 5, PI. XIV, is perhaps the caudal shield of a species of 

 the latter genus, and in that case is identical with Ph. latifrons, to which C. tuberndata decidedly 

 belongs.* 



4. Milne Edwards's species (pp. 318-328) have been already explained, with the exception of Cal. 

 Stokesii (p. 324, No. 13), (not Asaph. Stokesii of Älurchison — Sil. Syst. PI. XIV, Fig. 6), which is my 

 Phacops latifrons. 



* The figure referred to represents the tail of a Proetiis. — Editors. 



