NO. 1 DURHAM, BARNARD: EASTERN PACIFIC STONY CORALS 95 



reach the columella ; tertiary septa only slightly developed ; primary and 

 secondary septa approximately equally exsert, tertiaries half as exsert 

 as primaries and secondaries ; septa rounded above, inner edges of upper 

 one-thirds vertical, below this, sharply concave while descending to 

 columella; septal margins minutely flexuous and slightly granulated; 

 septal faces finely granulated; costae high, smooth, equally developed, 

 slightly wider than interspaces, primary costae usually extend to base 

 of corallum, secondary costae extend to within a short distance of 

 base, tertiary costae extend one-half to two-thirds the distance from 

 the top of the corallum to the base, some costae becoming interrupted 

 towards the corallum base ; columella blade-like at top, protruding slight- 

 ly above top of theca but not as far as primary and secondary septa. 



Remarks: This species differs from Sphenotrochus aurantiacus von 

 Marenzeller, by having only 3 cycles of septa and from S. intermedius 

 (Miinster), by the terminal septal triads being attached to the columella 

 at depth. The specimens are comparable to S. intermedius as figured by 

 Duncan (1874, pi. 41, figs. 1-5). 



The costae are variable on some specimens and may be very narrow 

 with wide interspaces. 



Dimensions of holotype: Height 4 mm, calice 1.5 by 2.5 mm. 



Holotype: AHF no. 20, with 2 paratypes. 



Type locality: Sta. 170-34, Stephens Bay, Chatham Island, 32 fms. 



Material examined: Stas. 143-34 (1), 170-34 (4), 1726-49 (2). 

 Bottom samples 400 (2), 401 (1), 406 (5), 409 (3), 411 (5), 430 

 (1), 431 (1), 437 (11), 438 (2), 439 (5), 441 (1), 442 (1), 444 

 (9), 448 (13), 450 (7), 451 (1), 452 (3), 453 (21), 458 (2), 460 

 (3), 463 (7), 468 (2), 471 (1), 472 (1), 473 (16), 479 (1), 483 



(1). 



Distribution: The Galapagos Islands; Sta. 1726-49, 1^4 mi south- 

 west of Cabeza Ballena, Lower California, 30 fms. Bathymetric range, 

 10-150 fms; 20 of the 29 records are between 15 and 45 fms. 



