POLYCLADS OF THE ATLANTIC COAST — HYMAN 453 



Habits. — Active, changeable, among shells and algae in shallow 

 water ; also pelagic, swimming at the surface. 



Neotype. — Pearse's type of '■'■Discocelis grisea,'''' U, S. N. M. No. 

 20186, selected as the neotype of Discocelis mutabilis Verrill, now 

 Coronadena mutabilis; two sets of serial sections also deposited in 

 U. S. National Museum. 



Remafrks. — As study of Pearse's specimens labeled Discocelis grisea 

 showed that the species is not a Discocelis but requires a new genus of 

 the Discocelidae, I have proposed the name Coronadena? Pearse 

 claims his new species grisea differs from mutabilis in color and eye 

 arrangement. As regards color, it was stated by him that the species 

 is gray with radiating light streaks (Florida specimens). In Pearse 

 and Littler (1938), some are said to be of this coloration, but others 

 (presumably North Carolina specimens) are described as gray around 

 the margin and somewhat speckled tan in the middle. In Pearse and 

 Walker (1939), the specimen from Cape Lookout, N. C, which was 

 called Discocelis grisea by Pearse and Littler, is now said to be Disco- 

 celis mutahilis. My examination of specimens from Florida and North 

 Carolina (including the Cape Lookout specimen, labeled Discocelis 

 grisea) has failed to show the slightest difference between them. I 

 have also been unable to find any difference in eye arrangement be- 

 tween Pearse's specimens and Verrill's figures and descriptions of 

 D. mutabilis. Unfortunately it has not been possible to find Verrill's 

 type specimen. The young specimens of *■'' Discocelis grisea)'' in the 

 Pearse collection are also very much like the young D. mutabilis 

 taken in the tow off Newport, R. I., and Woods Hole, Mass., by 

 Verrill in 1882. I am therefore of the opinion that grisea and muta- 

 hilis are conspecific and that the correct name of the animal is 

 Coronade'fia. mutabilis (Verrill). 



Family PLEHNIIDAE Bock, 1913 



Definition. — Craspedommata of oval or elliptical form and thick firm 

 consistency ; marginal band of eyes limited to anterior half ; cerebral 

 and tentacular clusters present, also usually some frontal eyes; all 

 eyes notably small (eyes altogether lacking in Flehnia arctica) ; 

 pharynx small, central; tentacles absent; accessory seminal vesicles 

 present*; prostatic vesicle free'^; penis unarmed; Lang's vesicle 

 present. 



2 Fuller description and illusti'ations ot this genus and species were included in a 

 paper I prepared for a Festschrift for Vejdovsky to be published in Prague. I read proof 

 on this paper late in 1939, but have since heard nothing of it. Owing to conditions in 

 Europe it is possible that it will never appear. 



* Accessory seminal vesicles are expanded terminal parts of the vasa deferentia with 

 definite muscular walls. 



° The prostate is said to be free when it is not part of the male canal but opens into 

 this by a duct. 



