NO. 6 CUSHMAN, MCCULLOCH : LAGENIDAE 297 



Stations: 1004, 1006, 1064, 1067, 1078, 1112, 1113, 1136, 1139, 

 1143, 1152, 1153, 1155, 1156, 1160, 1161, 1172, 1183, 1184, 1186, 1187, 

 1188, 1191, 1192, 1194, 1223, 1228, 1231, 1232, 1235, 1238, 1239, 1242, 

 207-2, 217, 223, 2023, 2029, 2033, 2063, 2064, 2065, 2098, 2100, 2131, 

 2137, 2142, 2156, 2157, 2160, 2162, 2164, 2166, 340, 406, 411, 413, 

 415, 416, 438, 450, 456, and 461. 



Distribution. — Off the Channel Islands with a depth range of 25 to 

 107 fms., the average depth being 57 fms. Off Mexico and in the Gulf of 

 California a range of 21 to 95 fms., the average being 50 fms. Off the 

 Galapagos Islands, the range is 20 to 80 fms., the average is 44 fms. 

 Numerous specimens were found at Clarion Island in 53 fms. 



Robulus limbosus (Reuss) 

 Plate 38, Fig. 8; Plate 39, Figs. 1-4 



Robulina limbosa Reuss, Sitz. Akad. Wiss. Wien, vol. 48, pt. 1, 1863 

 (1864),p. 55, pl.6, fig. 69. 



Robulus limbosus Cushman, Bull. 161, U.S. Nat. Mus., pt. 2, 1933, 

 p. 3, pi. 1, figs. 4-6; pi. 2, fig. 5. 



Test close coiled or tending to be slightly uncoiled, slightly evolute, 

 strongly biconvex in peripheral view, periphery strongly keeled ; chambers 

 usually 6 to 8 in the adult coil, those of the early portion often seen 

 through the somewhat clear umbilical region, of rather uniform shape 

 and increasing regularly in size as added, very slightly if at all inflated ; 

 sutures very distinctly limbate, slightly curved, and in general tangential 

 in position in relation to the earlier central portion; wall smooth, finely 

 perforate, translucent or in parts almost transparent; aperture radiate, 

 at the peripheral angle, usually with the ventral slit characteristic of 

 Robulus very distinctly developed. Diameter up to 2 mm. ; thickness up 

 to 0.60 mm. 



From the records this species is variable as are most species of Robulus. 

 Typical specimens are figured with others showing very considerable 

 variation. 



Stations: 225, 2016, 2144, 2164, 2169, 429, and 438. 



Distribution. — Five of these stations are off Mexico and Cedros 

 Island in 55 to 127 fms., the average being 100 fms. The two hauls off 

 Wenman and Chatham Islands, Galapagos, were in 100 and 35 fms. 

 respectively. The best record for numbers is off Cedros Island. 



