242 PALEONTOLOGY OF NEW-YORK, 



301. 2. CERAURUS PLEUREXANTHEMUS. 



Pl. LXV. Kigs. 1 a-n; and Pl. LXVI. Figs. I a - h. 



Ceraurvs pleurexantheinus. Gkeen, 1S32, Monograiih, pag. S4, fig. lU (Cast no. 33). 

 Calymene? sjieciosus, Dalman Hisinger, Leth. Suecica, Suppl. '2, 1S40, pag. 6, pl. 39, fig. 2. 



— — Dalman, Palaeaden, p. 74 ; Vet. Acad. Handlingar, 1S2G, p. 28.'5, who quotes Trilobites in- 



detenninahis, Sternberg in Verhandl. des Gesellsch. des Vaterl. Museums in 

 BohcMiie, pag. 85, tab. 1, fig. -5. 

 Amiihion gelathiosits. Portlock, Geol. Rep. Londonderry, 1843, pag. 289, pl. 3, fig. 4 a, i, c. 

 Compare Trilobites ignotits, Brongniart, Crust, fossiles, 1822, pl. 4, fig. 11. 

 Calymene ? verrucosa, Dalman, Vet. Acad. Handlingar, 1 826, p. 285. 

 Trilobites {Calymene!) verrucosa. Dr. Loven, Ofv. Vet. Ac. Forhandl., March 18-15, p. 52, t. 1, f. 5 a 6 c* 



Buckler crescentform, 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 foiu-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 lol)es, presents three large mammillary tubercles ; the first formed by an 

 obli(iue 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 tlie axis : the meeting 

 of these furrows leaves above them the second, or middle tubercle ( see Plate Ixvi, figs. 

 1 a and 1 e). Tiiis 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 Ixv, 

 fig. \ d e. From each uj)pcr angle of the labrum commences the facial suture ( more 

 distinctly sliown in Plate Ixvi, fig. lac), which, proceeding to the eye in a slightly 

 curving line, divides the oculiform tuljcrcle, and thence slightly ascending to the junction 

 of the marginal fillet, it bends abruptly downwards. 



• I have referred to this species, wliicli appears to be a true Ceraurua allied to the C. pleurexanthennis ; and since 

 its geological position is very similar, judging from the locality (Llandeilo), its occurrence is doubly interesting. 



