680 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.xxiii. 



Formation and localities. — Lower Cambrian. Linie.'?tone cong-lom- 

 erates at Bic and St, Simon, on the St. Lawrence River, Province of 

 Quebec, Canada. Also in Lower Cambrian limestones, l)oth l)edded 

 and cono-lomerate, on the ridge east of Troy. New York, and 1 mile 

 south of Schodack Landing, Rensselaer County. New York. 



BICIA WHITEAVESI, new species. 



This species is associated with B. gemma in a bedded limestone at 

 Tro3% New York. It differs from the latter in the dorsal valve by the 

 absence of the median ridge, the presence of a broad area, and the 

 presence in the interior of both valves of two large, circular, scar- 

 like spots, one on each side of the median line and just in front of the 

 area, that recall in appearance and position the posterior adductor 

 scars of Crania. The ventral valve is so much like that of B. gemma 

 that it is difficult to decide whether some shells should not be referred 

 to B. gemma. There is a gradual transition, in form and character of 

 the interior of the ventral valve, between the extremes represented in 

 B. gemma and the extreme form of B. whiteavesi. If it had not been 

 for the bosses of the dorsal valve associated with it I should have hesi- 

 tated to refer it to a distinct species. 



Formation and locality. — Lower Camlirian. Bedded limestone in 

 siliceous shale on ridge in the eastern su1)urbs of Troy, New York. 



OBOLUS, Additional notes on. 



Ohservatwns.-—T)\'. Mickwitz^ has given, in his exhaustive memoir on 

 Obolus, a ver}^ complete historical sketch and full description of the 

 genus and its subgenera so far as known to him. The material was 

 so well preserved, and the study was conducted with such care and 

 thoroughness, that our present knowledge of the adult shell of Ol)olus 

 is as complete as that of the adult shell of the recent Lingula. In this 

 note I shall present only such details as are essential to an under- 

 standing of the relations of (1) Obolus to Lingula; (2) Obokis to 

 Obolella; (3) Obolus to its subgenera. 



The student is referred to the memoir of Mickwitz for the literature, 

 history, a geological sketch of the Caml)rian formations of the eastern 

 Baltic region of Russia, a minute description of the external and inter- 

 nal characters of the shells of Obolus, an exposition of the relations of 

 Obolus to Lingula and Obolella, and detailed observations on Obolus 

 and its subgenera as known to him. 



Ohahis a)id Lingula. — After studying the species from American 

 rocks and a ver}^ good series from the typical localities in Russia, I 

 am prepared to agree with Mickwitz that Obolus should ])e referred 



^IJber die Brachiopodeugattimg Obolus Eiehwald: ]Mein. Acad. Imp. Sci. St. Peters- 

 bourg, 8th ser., IV, Xo. 2. 



