242 
PALAEONTOLOGY OF NEW-YOKK. 
301. 2. CERAURUS PLEUREXANTHEMUS. 
Pl. LXV. Figs. 1 a - n; and Pl. LXVI. Figs. 1 a - h. 
Ceraurus pleurexanthemus. Green, 1832, Monograph, pag. 84, fig. 10 (Cast no. 33). 
Calymene? speciosus, Dalman Hisinger, Letli. Suecica, Suppl. 2, 1840, pag. G, pi. 39, fig. 2. 
— — Dalman, Palasaden, p. 74 ; Vet. Acad. Handlingar, 1826, p. 285, who quotes Trilobites in- 
determinatus, Sternberg in Verhandl. des Gesellsch. des Vaterl. Museums in 
Bohemie, pag. 85, tab. 1, fig. 5. 
Amphion gelatinosus. Portlock, Geol. Rep. Londonderry, 1843, pag. 289, pi. 3, fig. 4 a, b, c. 
Compare Trilobites ignotus, Brongniart, Crust, fossiles, 1822, pi. 4, fig. 11. 
Calymene ? venucosa, Dalman, Vet. Acad. Handlingar, 1826, p. 285. 
Trilobites ( Calymene ? ) verrucosa , Dr. Loven, Ofv. Vet. Ac. Forhandl., March 1845, p. 52, t. 1, f. 5 a b c* 
Buckler crescent form, with a prominent connate articulation at the base, and the posterior 
angles extended into long curved spines ; eyes small, distant, sublunate, granulated (not 
reticulated ); glabella clavate, more or less convex, deeply four-lobed on each side, leaving 
the front one broader ; thorax with eleven articulations ; caudal shield with four (scarcely 
five) anchylosed articulations in the axial lobe, and three on each lateral lobe, the upper 
of these lateral articulations thickened and extended into a long curved spine, the others 
terminating in blunt points; surface entirely papillose or granulated, the buckler with 
scattered larger tubercles ; two ranges of small papillose tubercles along the central lobe, 
and three ranges of mammillary tubercles on each lateral lobe ; labrum ovate, attached to 
the front margin of the glabella by a straight suture. 
The above description comprises the most essential characters of this peculiar Trilobite, 
which is presented to us under a variety of obscure phases, no single specimen exhibiting 
all the essential characters. The whole surface, when perfect, is papillose. Upon all parts 
of the cephalic shield are interspersed small mammillary tubercles, and two similar ones 
on each articulation of the axial lobe, making two ranges of tubercles. Each articulation 
of the lateral lobes, presents three large mammillary tubercles; the first formed by an 
oblique furrow from the upper side of the articulation, downwards and outwards ; the third, 
by a furrow from the upper edge, downwards and inward, or toward the axis : the meeting 
of these furrows leaves above them the second, or middle tubercle ( see Plate lxvi, figs. 
1 a and 1 e ). This remarkable feature is unknown to me in any other trilobite. 
The ovate labrum attached directly to the front of the glabella, is shown in Plate lxv, 
fig. 1 d e. From each upper angle of the labrum commences the facial suture ( more 
distinctly shown in Plate lxvi, fig. la e), which, proceeding to the eye in a slightly 
curving line, divides the oculiform tubercle, and thence slightly ascending to the junction 
of the marginal fillet, it bends abruptly downwards. 
* I have referred to this species, which appears to be a true Ceraurus allied to the C. pleurexanthemus ; and since 
its geological position is very similar, judging from the locality (Llandeilo), its occurrence is doubly interesting. 
