THE SESSILE BAE1STACLES. 



173 



C. H. Townsend in 1890. The avails are smooth; radii rather nar- 

 row; parietes having an unusually large number of tubes, 13 to 17 

 in the rostrum. Spur of the tergum short. The scutum is about 

 typical. The largest examples have a basal diameter of 8 mm. It 

 has the external appearance of B. improvisus. 



The farthest south known for B. crenatus in the Pacific is Santa 

 Barbara, California. A few opercular valves and detached compart- 

 ments were found in debris washed from-Balamts tintinnabulum cal'i- 

 fornicus and the rock it grew upon. The valves seem nearly typical, 

 but the compartments are thin with smooth outer surface. Complete 

 specimens are needed to show the characters of the race. 



Pleistocene specimens of this species are in the United States Na- 

 tional Museum from Lawlors Lake, St. John County, New Bruns- 

 wick, Brunswick, Maine, and Douglas Island, near Juneau, Alaska, 

 where they were collected by Dr. Wm. H. Dall " 200 feet above tide- 

 water, in a trench of the pipe line near old mill in bowlder clay." 

 The specimens do not differ from recent forms found in neighboring 

 waters. EUROPEAN. 



EAST AMERICAN. 



1 Greenland specimens without nearer indication of locality are in the museum from the J. G. Jeffreys 

 and Isaac Lea collections, with others from unknown source. 



" Many specimens, some very fine groups, the gifts of Gloucester fishermen, are in the United States 

 National Museum from the Grand Bank of Newfoundland, the Banquereau and Georges Banks. As these 

 areas are fairly covered by the exactly located stations of the Fish Commission, the lots designated by banks 

 only are not entered here. 



