NO. 1 OSB URN : EASTERN PACIFIC BRYOZO A CHEILOSTOMATA 175 



their bases and for half or more of their length by long slits. There is a 

 short, flattened spine at each side of the aperture, with 2 or 3 very short 

 points; in the ovicelled zooecia these spines are more or less fused with 

 the sides of the ooecia. In the absence of ooecia there is a small median 

 spine on the distal border. There are no avicularia. 



The ooecia are hemispherical, prominent and wide open; the ecto- 

 oecium does not form a complete cover but leaves a somewhat v-shaped 

 frontal area which, in complete calcification, terminates in a pointed 

 umbo at the top. The ooecium is about 0.20 to 0.25 mm broad by 0.13 

 mm long. 



The general appearance is that of Savigny's figure of Flustra aragoi 

 Audouin, with the exception that the ovicell is somewhat longer and the 

 lateral oral spines are short and end in 2 or 3 tubercles, instead of being 

 branched in alcicorn fashion and extended backward on the sides of the 

 aperture. There appears to be a tendency toward a greater number of 

 costae, but Savigny's figure 1, shows 5 costae on a side. Marcus, 1938 :30, 

 has recorded aragoi from Santos Bay, Brazil, with two pairs of costae 

 and 3 to 4-branched lateral oral spines. Harmer, 1926:473, described 

 aragoi from the East Indies with 3 to 5 pairs of costae and short-bifurcate 

 oral spines. Also Canu and Bassler (1928-35) have described, from north 

 of Cuba, M. petasus, in which the costae are usually 4 to 6, the lateral 

 oral spines short-bifid (occasionally trifid in the writer's specimens from 

 the Caribbean Sea), but the central area of the front is usually more 

 closed and a lacunae smaller. I am inclined to the view that all of those 

 are to be considered varieties of aragoi, especially as I have a colony from 

 the Caribbean which is almost the exact counterpart of Savigny's figure 

 with the 4-pronged lateral spine which extends backward on the side of 

 the aperture, sometimes even fusing with the proximal branch of the first 

 costa; but in the same colony there are occasional shorter trifid spines. 



Type, AHF no. 43. 



Type locality, Hancock Station 924-39, Socorro Island, 18°41'52''N, 

 110°55'20^'W, 17 to 46 fms. Also at Stations 129-34, Socorro Island, 

 and 135-34 and 219, Clarion Island, west of Mexico; 143-34, Wenman 

 Island and 224, Albemarle Island, Galapagos; 270, Angel de la Guardia 

 Island, Gulf of California; and 224, San Benito Island, Lower Cali- 

 fornia. Bathymetric range, 2 to 100 fms. 



