108 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 14 



The B zooecia, to use Harmer's term for the slightly modified 

 avicularian zooecia, are not larger than the largest of the normal zooecia, 

 but are broader distally to accommodate the large operculiform mandi- 

 ble; the cryptocystal lamina is shorter and the frontal process also, leav- 

 ing a much larger opesia; the distal mural rim is raised into a shallow 

 hood and the tubercles are wanting at the distal corners. The mandible 

 (B operculum) is rounded distally and on the sides, well chitinized; the 

 main sclerites are only slightly arcuate outward, running from the condy- 

 lar attachment to the distal border where they fail to meet by about 0.07 

 mm, the gap being bridged by a thinner extension of the chitin. There 

 are no teeth on these sclerites, but there is a strong flange a little beyond 

 the point of attachment to the condyles. An accessory strong rib curves 

 inward proximally from a short distance above the attachment and reaches 

 the proximal border where it is connected with the ectocystal sclerite on 

 each side. The border sclerite is heavy distally, where it bears 8 strong, 

 short teeth, but fades out before reaching back to the condyles. The 

 mandible is somewhat intermediate between the U and V or Y types of 

 Harmer. It measures 0.26 mm long by 0.30 mm wide. 



Because of the uncalcified polypide tube, except for the roof, the lack 

 of lateral connections with the frontal process, and the narrow circum- 

 opesial cryptocyst, this appears to be a very primitive member of this 

 genus. There can be no doubt of its generic relationships, however, since 

 the differentiation of the A and B zooecia is characteristic. Harmer 

 (1900:253) described S. simplex from the Amirante Islands, which re- 

 sembles cornuta in the characters just mentioned, but which is otherwise 

 very different. 



Type, AHF no. 27. 



Type locality, off Acapulco, Mexico, 15 fms. Captain Fred S. Lewis, 

 collector. Also Gulf of Panama, Galtsoff collection, on shells of pearl 

 oysters, (station 26, Coiba, Canal Coibita, northern end, south of Isla 

 Rancheria). 



Genus LABIOPORELLA Harmer, 1926 



Labtopora Levinsen, 1909:171, 174 (preoccupied). 



Zooecia with distinctly raised walls. Gymnocyst wanting. Cryptocyst 

 porous, not extending as a shelf around the opesia. A vertical cryptocystal 

 lamina separates the proximal and distal cavities, perforated near the 

 middle by the polypide tube; inner borders of the walls heavily granu- 

 lated or crenulate. Avicularia large, vicarious, with spatulate mandibles. 

 No ooecia. Multiporous septules present. Genotype, Labiopora crenulata 

 Levinsen, 1909. 



