494 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 14 



in all details to that of other recent species of Schizmopora while that 

 of Osthimosia is imperforate. As far as the frontal calcification is con- 

 cerned, in the abundant material at my disposal I can find no essential 

 difference, in younger stages the frontal is as smooth as in any of the 

 Schizmopora species, though the olocyst does become more heavily cal- 

 cified and somewhat roughened with age. For these reasons I place the 

 species in the genus Schizmopora. 



Hancock Stations: 20 stations about the Galapagos Islands as follows: 

 155-34, 317-35, 450 and 483 at Albemarle Island; 170-34, 432, 451 and 

 467 at Charles Island; 173, South Seymour Island; 182-34 and 446 at 

 James Island; 201-34, 473 and 488 at Hood Island; 310-35 and 311-35 

 at Bindloe Island ; 810-38 and 484 at Barrington Island ; 400 at Gardner 

 Island; 411 and 416 at Duncan Island. The species appears to be very 

 abundant about the Galapagos archipelago with the bathymetric range 

 from 5 to 160 fms. The only stations at which it appeared outside of the 

 Galapagos area were at Station 264-34, White Friars Islands, off Tena- 

 catita Bay, Mexico, 17°30'50"N, 101°29'56''W, at 25 fms; 450-35, 

 Secas Islands, Panama; and 1250-41, San Benito Islands, west of Lower 

 California, 28°17'15"N, the northernmost latitude. 



Schizmopora margaritacea (Pourtales), 1867 

 Plate 62, figs. 7-9 



Vincularia margaritacea Pourtales, 1867 :1 10. 

 Cellepora margaritacea, Smitt, 1873 :53. 

 Schizmopora margaritacea, Osburn, 1940:460. 



One small dead portion of a colony of what is presumably this species 

 conforms in all the characters that are present. Unfortunately the 

 specimen shows no large avicularia. The zoarium is erect and branched 

 from a narrow encrusting base, the branches terete and narrow, diameter 

 about 0.80 mm, with zooecia evenly distributed on all sides; the broken 

 portion, 10 mm in length, shows the bases of four branches. The 

 zooecia are elongate-oval, distinct and somewhat inflated near the tip 

 of the branch, more basally the outlines are indistinct, 0.60 to 0.65 

 mm long by 0.35 to 0.40 mm wide. The aperture is nearly circular with 

 a broad, shallow sinus, width about 0.12 mm. Proximal to the aperture 

 and asymmetrical is a small avicularium on the distal side of a small low 

 umbonate process, both of which become more or less enclosed in the 

 secondary aperture in advanced calcification. Smitt mentions 4 minute 

 oral spines, but I have found evidence of only two. 



