OF THE SPECIES. 99 



University collection and three in Sack's museum. The body rings appear smooth, or at least the 

 lateral lobes are so ; the caudal shield, on the contrary, exhibits a distinct fine granulation. 



2. I formerly included in this group Cahjmene clavifmns, Dalm. [Pahi-ad. 75. 2, Sar-i his, 1835. 

 339, Tab. IX, Fig. 8), Tril. sphd'ricns, Boeck (Gaea norw. i, 14), P/mcops xp/ia-ricus, Emmr. {Dissert. 

 20. 3), and erroneously connected with it Asaph, diibiiis, Münster [Beitr. v, 113, Tab. X, Fig. 12). 

 The latter is, as Dr. Beyrich has shown, the hypostoma of a Ckierurus ; the former, however, is a fragment 

 of a peculiar Trilobite, which Dr. Beyrich includes in his new genus Sp/ia>re.vochus. 



3. Cahjmene bellatula, Dalm. {Paheud. 3G. 2, Tab. I, Fig. 4, Rising. Leth. Stiec. ii. Tab, I, Fig. 5, 

 Milne Edwards, Ciiist. iii, 321. 7, Emmr. Dissert. 31. 8), likewise does not belong to my genus 

 Cyphaspis, as I formerly supposed, judging from a damaged specimen, but must be referred to a 

 peculiar genus which Dr Löven {ante, p. 1 10) calls Cyhele, and in which he also includes the Calym. 

 verrucosa, Dalm. {Arsber, etc. 1827. 52), together with Trilob. velutus, Schloth. {Petref. supplement ii, 

 40, Tab. XXII, Fig. 5), found at Revel. I must refer to Dr. Löven's treatise for the characters of 

 this new genus, which has been very thoroughly described by him.* 



Genxs 15. — Proetus, Steiningcr, (^Eonia, Burmcister; Gerastos, Goldfuss.) 



Cephalic shield semicircular, surrounded by a thickened margin ; the posterior angles 

 do not project perceptibly; the glabella is very convex, parabolic, rounded at the anterior 

 part, undivided, without any lateral lobes ; at the posterior part it is as broad as the margin, 

 to which it is immediately joined. The facial suture projects over the anterior cephalic 

 margin on a line with the eyes, is thence directed towards the eye, forms the covering plate, 

 and runs at first straight, afterwards in an S- shaped curve, to the posterior margin, which 

 it penetrates beyond the centre, in an oblique direction towards the external part. 



Eyes of moderate size, very prominent, smooth, joined rather closely to the glabella. 



Body axis ten-jointed, the joints gradually more narrow towards the posterior part, 

 strongly arched, abruptly separated from the lateral lobes by a peculiar furrow, these lobes 

 having an oblique indentation. 



Caudal shield corresponding with the cephalic, but smaller, the axis highly arched, 

 short, distinctly articulated, the sides furnished with slight furrows or obsolete ribs, 

 the margin even, but having a very acute angle. The surface of the shell almost 

 smooth, but with distinct traces of granulation on the glabella, and on the cheeks beneath 

 the eye. 



Remark. — Prof. Goldfuss described species of this genus under the name of Gerastos, but con- 

 nected with them, as I also did, other Trilobites which do not belong to the group. Mistakes of this 

 kind would have happened less frequently, if former authors had furnished us with as distinct 

 illustrations as we have at present in my Monograph, and in the works of Goldfuss, Löven, Beyrich, 

 and others. 



P. Cuvieri : Protuberantia verticis latissima, longitudine vix angvistiori, obsoletissime granulata ; 

 angulis scuti cephalici obtusis. Long. 1". Tab. Ill, Figs. 1, 2. 



* The following are the characters given by Professor Löven for his genus Cyhele : — Caput breve 

 latum. Scutum centrale sublunatum, latum. Sutura pone oculum subrecta, ad angulum ducta. 

 Oculi minuti arcu infraorbitali elevato, angusto. Thorax articulis (in una specie) duodccira. Terga 

 convexa. Pleuraa sulco longitudinal! in partem anticam dins» syndesmalem breviorem, et posticam, 

 magis minusve productam. Pygidium thoraci ex parte conforme, minutum, ex articulis numerosis 

 coalitis, quorum basales aliquot majores, pleuris prrediti, reliquis in caudam lauceolatam arctius connatis. 

 Oversii/t af Kongl. Vetenskap. Arnd. Fork. 1815, No 4, p. 110. — EniTORS. 



