1917.1 NATURAL SCIENCES OF PHILADELPHIA. 137 



THE ANATOMY OF AN EOLID, CHIOR^RA DALLI. 

 BY HAROLD HEATH, 



In 1852 Gould^ described a species of nudibranch, dredged in three 

 fathoms of water at Fort Discovery, Puget Sound, establishing for 

 it a new genus, Chiorcera, whose translated diagnosis is as follows: 

 Body limaciform, head very large, pedunculate, semiglobose; oral 

 face ventral, discoidal; mouth longitudinal, surrounded by a double 

 series of cirri; cephalic tentacles foliate, retractile; branchial folds 

 fan-shaped, arranged in a series on each side; genital opening removed 

 from the almost dorsal anus." The species is further characterized 

 by a pearly and whitish-colored body finely reticulated with orange. 

 The cirri likewise are orange colored, and the cephalic tentacles are 

 capable of retraction within a special sheath. The total length of 

 the body is five and one-fourth inches. 



On the 26th of July, 1913, I collected a number of specimens of 

 what appear to be a new species of this genus in Rose Inlet on the 

 eastern shore of Dall Island in southeastern Alaska. Two days later 

 a few other individuals were taken in Hecate Strait near Hetta on 

 the western coast of Prince of Wales Island. To Mr. W. F. Thomp- 

 son I am indebted for additional material collected at Echo Harbor 

 and Sewell Inlet on the eastern coast of the Queen Charlotte Islands. 



The present species appears to be largely confined to the littoral 

 zone, as the larger number of specimens were collected on algae in 

 shallow water. Nevertheless, a considerable number were found 

 swimming near the surface, in some instances fully three hundred 

 yards from shore. As they crawl about the great head is frequently 

 contracted with considerable violence, possibly for the purpose of 

 dislodging small organisms which serve as food. Sections of the 

 alimentary canal, however, show it to be entirely empty, in all of the 

 individuals critically examined, with the exception of one containing 

 a few diatoms, so that we have little information indeed concerning 

 the usual bill of fare. In the act of swimming the head is contracted 

 as much as possible and the body is strongl}- flexed from side to side. 

 Large numbers of eggs were found attached to "eel grass" and 

 imbedded in gelatinous, spirally wound folds after the fashion of 

 manv nudibranchs. 



1 U. S. Exploring Expedition, vol. 12, pp. 309-311. 



