12 



PALEONTOLOGY OF NEW YORK. 



mksM 



FIG. 8. 

 Lingiiht priracletus, sp, nov. 

 Interior ol' i)edicle-\alve. 



Flli 9. 



Lingula Mdie, Hall. 



Intevioi* of bracliial valve. 



of these beds, but is described in 

 tlie concluding pages of this work 

 iis L. paracletus, sp. nov., has 

 aflbrded the most complete and 

 satisfactory representation of the 

 system of muscular scars. The 

 pedicle-valve here figured is drawn 

 from a cast of the interior, which 

 shows not only the centrals (A), 

 middle laterals (k), but the dis- 

 tinctly specialized outside laterals 

 (/), anterior laterals ( /), the transmedians (/), and the great umbonal (g). 

 Even the asymmetry of the transmedians (?) is apparent iu the unei[ual 

 size of the impressions, that on the left in the figure (corresponding to the 

 right, when looking into the interior of the valve) being noticeably larger than 

 its correlate, in the brachial valve, the scars are essentially like those in the 

 corresponding valve of L. Melie, shown in the accompanying figure, but are not 

 placed quite so far back. Here the laterals (/, k) and transmedians (?) are 

 coalesced, and show a tendency to spread transversely over the visceral region, 

 a feature sometimes noticeable in other palaeozoic species, and probably of 

 similar nature to that seen in Barroisella suhspalulata (Plate I, fig. IG). 



As lar as the vascular markings of the brachiocoele in the fossil species have 

 been observed, the}' appear to have been in full agreement with those of the 

 living type. In />. Whilii, L. Elderi, L. punctata, L. cuneata, and L. lamellata the 

 large pallial sinuses are to be seen passing forward from the parietal band, or 

 the position of the compound lateral scars, approaching each other imtil they 

 nearly or quite meet in front. The outer ramifications from these large trunks, 

 and, in L. Elderi and L. cuneata, the inner also, are discernible. In the brachial 

 valve of L. Elderi are seen the vascular impressions of the pleurocades, which 

 lie in the post-lateral portion of the internal cavity, outside the parietal 

 band. \n L. Procteri and L. paracletus, the anterior vascular branches appear 

 to radiate from the edge of the central muscles, as though the pallial trunks 



