VERRILL, SYNOPSIS OF POLYPS AND CORALS. 181 



XII. Synopsis of the Polyps and Corals of the North Pa- 

 cific Exploring' Expedition, under Commodore C. Ring- 

 gold and Captain John Rodger s, U. S. N.^from 1853 to 

 1856. Collected by Dr. Wm. Stimpson, naturalist to the 

 Expedition. With Descriptions of some additional Spe- 

 cies from the West Coast of North America. By A. E. 

 VERRILL. 



PART II, ALCYOXARIA. With two Plates. 

 [Communicated February 29, 1865.] 



The specimens upon which the following descriptions 

 are based were mainly collected by Dr. Wm. Stimpson 

 while acting as naturalist to the expedition. 



They were for the most part preserved in alcohol, and 

 many are accompanied by notes and drawings of the soft 

 parts, which have been reproduced in the plates. In most 

 instances I have given the descriptions of the colors of 

 perishable parts, as well as notes on the mode of occur- 

 rence, in Dr. Stimpson's own words. 



Descriptions of a few species in the collection of the 

 Smithsonian Institution and the Yale College museum, 

 from the Pacific Coast of America, have been added, for 

 the sake of making- thepaper more complete. 



SUBOKDEK, PEraATULACEA, 

 FAMILY, PENNATULID^E. 



PTEROMORPHA EXPANSA Verrill. 

 Plate 5, figure \. 



The pinnate portion is broad ovate, abruptly rounded be- 

 low ; peduncle, or basal portion, thick, swollen, a little less 

 than half the entire length. Pinnae crowded, about thirty- 

 two on each side, long and wide, somewhat thickened, an- 

 gular, the naked posterior margin somewhat concave, the 

 anterior rounded and supporting numerous small polyps, 

 and strengthened with sharp spines, which are often in clus- 

 ters of two or three. The outer half of the sides of the 



ESSEX INST. PROCEED. VOL. IV. X. 



