Horizon of Dr. Scolder s Dithyrocaris. 



271 



and that the specimens were got in a peculiar limestone -which was 

 formerly quarried on Gallowhill Farm, 1^- miles to the north-east of 

 Paisley, and that both Sir. Armstrong's and Mr. Neilson's statements 

 as to the locality where they were found are erroneous. 



The Type-specimens of Dithyro'garis tricornis and D. testudixea. 



The type-specimens of the two species of Dithyrocaris were 

 originally presented to the Anderson College Museum by Dr. Scouler, 

 and some years ago were gifted, along with other specimens, to 

 Kelvingrove Museum by the Governors of the Royal Technical 

 College. D. tricomis shows the two valves of the carapace lying 

 in an almost symmetrical position, but reversed so that the anterior 

 part is approximately in the position that the posterior part ought to 

 be, a phenomenon not unusual in decaying and floating Phyllopods. 



Fig. 1. — A. Dithyrocaris tricomis, Scouler. B. D. testuclinea, Scouler. 

 From the original drawings in Scouler' s paper. The type-specimens are 

 now in Kelvingrove Museum. 



The three somewhat obscure abdominal segments and a tail with 

 three spines project from the lower part of the front of the carapace. 

 The gastric teeth are exposed through the test. 



In Dithyrocaris testuclinea the broad oval carapace is semi-elliptical 

 in shape. The two valves lie in opposition by their dorsal edges, 

 and overlap irregularly towards the lower half of the dorsal region, 

 lu both valves the central border is seen to terminate in a small 

 obscure spine. A strong ridge showing the characteristic rugose 

 structure of the overlapping chevron-shaped scales runs down the 



