100 SYSTEMATIC ARRANGEMENT 



Jlpf- Steininger, Bemerk, ii. d. Vorst. d. Eifel. Trier, 1831. 4, No. 52. 3Iem. de la 

 Soc. Geol. de France, i, 359, No. 52, PI. XXI, Fig. 6 (1834). Gerastos hevif^afns, 

 GoLDF. Leonh. and Bronn. n. Jahrb. 1843. 557, Table IV, Fig. 3. 

 Locality. — A yellowish-gray limestone of the Eifel, near Blankcnheim, according to 

 specimens in Sack's and the Academy collections. 



Glabella not very convex, without distinct granulation ; it does not reach the anterior 

 maro-in, which is reflexed : eyes rather behind the centre, surrounded externally by an 

 indented I'ing, the cheeks beneath them distinctly granulated, their angles rounded. Body 

 rings not remarkal^le ; the caudal shield rather small, and flat like the axis, the latter nearly 

 eight-jointed, but the last joints indistinctly separated ; the sides furnished with six, more or 

 less deeply-marked, furrows. 



Remarks. 1 . The Trilobite above described I formerly considered to belong to Calymene conchma, 



Dalm. iPalmad. 40. 7, Tab. I, Fig. 5 ; Milne Edw. Crust, iii, 325. 16 ; Asap/i. cone. Emmr. Dissert. 

 35 19). Dr. Löven, however, has since published a very accurate description of Dalman's species 

 (49 Tab. I, Fig. 2), and proved that it is not identical with Proetus Cuvieri. But he is of opinion 

 that both Trilobites belong to the same genus, which I cannot admit. I prefer separating Dalman's 

 species from the species of Steininger, giving the new genus my former designation of Jeoiiiu, and 

 distinguishing it from Proetus by the following characters : 



Glabella (which is shaped like a violin) has at each side three slight furrows, is contracted behind 

 in a pedunculated stape, and furnished with two little tubercles close to the peduncle. The angles of 

 the cephalic shield terminate in long spines. 



The eyes are oblong, lunate, and flatter than in the other. The axis of the body is comparatively 

 narrower, but likewise ten-jointed. 



The caudal shield is not so obtuse, its axis longer and narrower, and its sides have deeper radi- 

 ations. 



The following species belong to this new genus : 



1. Ae. concinna [Proetus concinnus, Löven 1, 1; Calymene cone. Dalm.). The cephalic shield I 

 have copied from Löven's figiu-e. Tab. V, Fig. 8. 



2. Ae. Stokesii [Asap/i. Stokesii, Murch. Sil. Syst. ii, 625, PL XI Y, Fig. 6; Löven 50, Tab. I, 

 Fio-. 3). From the figure by Löven I have copied the cephalic shield. Tab. V, Fig. 5. 



3. Ae. verticuUs, Mihi, Tab. V, Fig. 9 (Gerastos cormitvs, Goldf. 558. 3, Tab. Y, Fig. 1). This 

 species is nearly related to the former, and perhaps identical. I have formerly described it from an 

 imperfect specimen as Trilobites verticalis, and therefore did not recognize it properly ; the present 

 fio-ure is more correct. The glabella is flat and fiddle-shaped, becomes gradually narrower towards the 

 anterior part, and exhibits at each side three oblique sulcations, of which the posterior rans in a curve 

 towards the posterior margin, nearly reaching it. Traces of granulation may be seen on its summit. 

 The oblong, lunate eyes correspond to the two posterior cephalic lobes ; they are externally surrounded 

 at their base by a furrow. The margins of the cephalic shield form a protuberance, which passes over 

 at the angle into the long powerful spine, but is sulcated at the upper part. The body joints are 

 short but rather broad, uarrower, however, than the lateral lobes. The caudal shield is rather less 

 than a semicircle, its axis acutely pointed, seven-jointed ; the sides have five flat elevated ribs, their 

 extremities gradually becoming broader and indented by an additional radiated furrow. 



Occurs in the Eifel near Bensberg (Sack's collection). 



2. Calymene diops, Green [Mon. 37, Fig. 2 ; MontJily Amcr. Journ. of Geol. 559, Tab. XXII, 

 Fig 2; Milne Edwards, Crust, iii, 323. 10; Harl. Med. and Plnjs. Res. 301). The figure, Tab III, 

 Fi^. 5, is copied from the specimen in plaster of Paris of the Berl. Museum ; this species seems rather 

 to belong to the new genus Aeonia than to Proetus, and I shall therefore not attempt a further description 

 of it until I have accurately examined original specimens. The figure is sufiSciently recognizable. 



3. Gerastos granulosus, Goldf. (558. 2, Tab. V, Fig. 4), belongs decidedly to Proetus. It is 

 distinguished from Pr. Cuvieri by its more elongated and more strongly granulated glabella, and by 

 the more pointed angles of the cephalic shield. 



