Vol. 52.] GEOLOGY OF THE NEIGHBOURHOOD OF CARMARTHEN". 537 



Measurements of Pel/ura punctata, sp. nov. 



(These measurements are of a medium-sized but almost perfect 

 specimen.) 



Inch. 



Total length -94 



Length of head 34 



Length of thorax -52 



Length of tail -08 



Width of head -40 



Greatest width of glabella 22 



Width of glabella at base '20 



Greatest width of body -44 



„ „ pleura '14 



axis -20 



Distance of fulcrum from axis -04 



Genus Olenus, Dal. Subgenus Parabolinella, Brog. 



Parabolinella, sp. nov. (PI. XXVI. figs. 11 & 12.) 



This trilobite presents sufficient differences from the P. rugosa 

 described by Brbgger to admit of its being considered a new species 

 or variety. As we have, however, only one specimen, and that is 

 somewhat imperfect, we prefer to withhold a complete determination 

 until better specimens are found. The present example consists of 

 the glabella and fixed cheeks only ; it is a good deal larger than 

 Brogger's figured specimen of P. rugosa, being -46 inch long and 

 •5 inch wide. As in P. rugosa, the glabella narrows slightly 

 forwards, but it is somewhat wider in proportion to the length 

 than is the case in that form. A very small portion of the anterior 

 margin is seen on the right side. Here, too, there are three prin- 

 cipal pairs of glabella-furrows, of which each anterior furrow is 

 shallower in the middle ; the two posterior pairs being bent sharply 

 backward, and also branched. The branching is, however, not 

 quite identical with that which occurs in the furrows of P. rugosa, 

 as the second branch of the posterior furrow deepens more towards 

 the middle, where it joins the first branch, and less towards the 

 1 exterior side of the glabella. The most striking difference between 

 the two forms lies in the structure of the additional pair of furrows, 

 which occurs between the posterior pair, mentioned above, and the 

 neck-furrow. This pair is very distinctly seen, and each furrow 

 is double instead of being single as in P. rugosa; thus a nanow 

 raised piece is included between the two forks. The eyes are 

 large and occur in the same position as those of P. rugosa. The 

 fixed cheeks are very narrow, but widen out posteriorly to more 

 than | the width of the glabella and have a well-marked neck- 

 furrow. The neck-segment resembles that of P. rugosa, but has no 

 central tubercle. 



Locality and Horizon : Nant-y-Glasdwr, Carmarthen. Tremadoc 

 Slates. 



2o2 



