88 PROCEEDINGS OF TIIE GEOLOGICAL SOCIETY. 



Peltocaris aptycholdes. Fig. 1. 



Dithyrocaris aptychoides, Salter, Quart. Journ. Geol. Soc. vol. viii. 

 p. 391, pi. 21. fig. 10. 



The broad, rounded-oval shield measures only 5 lines in length, 

 by about 44 lines in breadth ; so ,,. ., -. , . , , . , 

 that it is not a true circle, but ap- Yl %' l—P^cans aptychoides, 

 pears nearly like one. The rostrum, natural slze and enlarged, 

 as broad as long, and of a para- 

 bolic shape, is just one-third the 

 whole length. The body and ap- 

 pendages have not yet been found. 



The division along the dorsal line 

 is continued as an open fissure for 

 a part of the length, then as a 

 narrow line ; but the valves seem 

 to have been so far connected (by 

 membrane ?) that they occupy their 

 original place; and in one case only, 

 I think, have I seen the valves dissevered, never bent down. Imme- 

 diately behind the rostrum, in this specimen, what should be the 

 apex of the valve is circumscribed (a) and apparently cut off by a 

 deep furrow, or suture, from the rest. The two umbones, if they 

 may be so called, are in this way isolated. It may not be so in all 

 specimens ; but this notched umbone existed also in the larger speci- 

 men, figured as above quoted, and which is also, by favour of Pro- 

 fessor Harkness, in the collection of the Museum of Practical Geology. 



Locality. Anthracite-shales (Llandeilo-flags), Dumfriesshire. Mu- 

 seum of Practical Geology. 



Peltocaris? Harknessi, sp. nov. Fig. 2. 



A fragment, 2 inches long, in the same black Anthracite-shale 

 which afforded the Peltocaris ajptycJioides, was sent me by my friend 

 Professor Harkness many years back ; and I then made the accom- 

 panying drawings (fig. 2) and description. I hope the specimen is 

 still safe in his cabinet. 



It is a fragment of a much larger carapace than that of P. apty- 

 choides, probably 3| inches at least in length. Only the ventral edge is 

 shown, and that for a short distance, covered by oblique marginal lines, 

 which run backwards, while these are crossed by ventral striae, 

 transverse to the general direction of the carapace. The latter are 

 more remote than the marginal lines, and meet or cross these at an 

 angle of about 85° or 90° ; while in the region unoccupied by the 

 marginal striae, the cross lines are themselves interrupted and fre- 

 quently decussated by short striae in an opposite direction. These 

 short striae may possibly be structural. But they are all exhibited 

 on the fossil ; and I have introduced them accurately in the figure. 

 Fig. 2, B, is a magnified portion. The marginal lines are closer than 

 the vertical, and more wavy, and they occupy the undefined border to 

 the exclusion of the others ; but they are distinctly traceable for a 



