289 

 Thracia semiplanata, Whiteaves. 



Thracia semiplanata, 1884. This volume, pt. 3, p. 221, pi. 29, fig.s .5, 5, a-c. 



East end of Maud Island, five good specimens ; and Creek neax* Camp 

 Robertson, two miles south of Yakoun Lake, at an elevation of about 

 600 feet above the level of the sea, one small specimen ; all collected by 

 Dr. Newcombe in 1895. 



Pleuromya papyracea, var. Carlottexsis. 



Plcuromiia Carlottensis, Whiteaves. 1870. This volume, pt. 1, p. 57, pi. 9, fig. 8. 



Plcuromiia suhcompressa, Whiteaves. 1884. Ibid., pt. 3, p. 22, pi. 29, fig. 6. But pro- 

 bably not Myacites (Pleuronuia) suhcompressa. 

 Meek, if that is a Jurassic species. 



Plcuromm suhcompressa, \-ay. Cai'lottensis, Whiteaves. 1884. Ibid., pt. 3, p. 223, pi. 29, 



figs. 7, and la. 



South side of Alliford Bay, C. F. Newcombe, 1895 : one good 

 specimen. * 



The types of Pleuromya papyracea, Gabb, which are now in the 

 Museum of the .Academy of Natural Sciences of Philadelphia, have been 

 kindly lent to .the writer by Dr. H. A Pilsbry. They consist of a nearly 

 perfect and well preserved cast of the interior of both valves of an 

 apparently adult shell, foi'ty-five millimetres in length, with small 

 portions of the test preserved, (evidently the original of Plate 29, fig. 66, 

 of the second volume of the Palaeontology of California); of an imperfect 

 cast of the interior of a half-grown right valve ; and of three very small 

 casts of the interior of both valves, the largest of which is not more than 

 three-quarters of an inch in length. 



From a direct comparison with these specimens it would seem that all 

 the concentrically ribbed Pleuromyiv from the Queen Charlotte Islands 

 that are described and figured in the first and third parts of this volume 

 should pi'obably be regarded as representing a local and coarsely costate 

 or plicate variety of P. pajiyracea. 



Dr. Stanton has expressed the opinion* that Pleuromya Uavigata, 

 Whiteaves, is a synonym of P. papyracea, but, in the writer's judgment, 

 these two forms are quite distinct, P. Imvigala being much smaller than 

 P. papyracea, different in shape and almost smooth, its outer surface 

 being -marked only with a few concentric lines of growth. 



Pleuromya LyEvioA'M, Whiteaves. 



Pleuroiiim (suhcompressa? var.j Icevujata, Whiteaves. 1884. This volume, pt. 3, p. 224> 

 pi. 30, 1, 1, a-c. 

 The specimens from Alliford Bay and Maud Island, and probably also 

 those from the Iltasyouco River and " Lower Sandstones" of the south 



*In a foot note to page 18 of Bulletin No. 1.33 of the United States Geological Survey. 



