460 PROCEEDINGS OF THE NATIONAL, MUSEUM vol.89 



very variable. Typical arrangement, shown in my figure referred 

 to above, is pair of groups of two to several eyes each between the 

 tentacles, and another pair of two to several eyes each anterior to 

 these; may also be a few eyes behind these four groups, over the 

 brain ganglia. Some specimens in the Pearse collection, collected 

 in Florida and at Seabrook, Tex., have a large number of cerebro- 

 frontal eyes, beginning behind the tentacles, extending forward be- 

 tween the tentacles and then spreading fanlike toward the anterior 

 margin, where they merge with the marginal band (fig. 25, c). 



Color. — ^Very variable, cream, yellow, reddish brown, brown, olive, 

 or gray, veined or reticulated with a lighter color, or finely maculated 

 with a darker color on a lighter ground; with a middorsal light 

 stripe, usually more noticeable toward the posterior end. 



Digestive tract. — Pharynx about central, relatively small, moder- 

 ately ruffled; digestive branches anastomosed into a reticulum in the 

 periphery of the body (hence incorrectly shown by Pearse). 



Reproductive system. — Described and figured by Hyman, 1939a, 

 fig. 3, p. 133. Typical of the genns but differs from other species 

 in that the copulatory complex is very close to the posterior margin. 



Distribution. — Texas to Prince Edward Island, very common south 

 of Massachusetts. 



Habits. — Littoral, among barnacles, oysters, and shells, on pilings, 

 under rocks ; feeds on oysters and barnacles. 



Remarks. — Pearse's attempt to revive the genus Eustylochus can- 

 not stand, since this genus was based on '''"PlanocercC elliptica., and I 

 have shown that this species is a typical Stylochus (Hyman, 1939a). 

 In that paper I overlooked the fact that Meixner, in 1907, investigated 

 the same species and found it to be a Stylochus. There cannot be 

 any doubt that the present species is Girard's Planocera ellipflca, 

 since his figures of this (1893) could not pertain to any other poly clad. 

 In 1853, Girard, collecting off the Carolina coast, named gray speci- 

 mens '"''PlanocercC nehulosa., but obviously these are merely a color 

 variation of Stylochus ellipticus. Pearse (1938) repeated the at- 

 tempt to separate southern specimens as a new species, ''''Eustylochus''* 

 meridionulis^ on the basis of color and arrangement of the cerebro- 

 frontal eyes. If this were a valid species, its name would obviously 

 be nehulosa Girard ; but the points cited by Pearse are already covered 

 in Verrill's account of the variations of S. ellipticus. My examina- 

 tion of Pearse's specimens labeled Eustylochus mendiondlis., including 

 serial sections made from some of them, has failed to show any grounds 

 whatever for separating them from S. ellipticus. I have also sec- 

 tioned the copulatory apparatus of one of the Seabrook, Tex., speci- 

 mens mentioned above as having a large number of cerebrofrontal 

 eyes, as in fig. 25, <?, and found it to be identical with that of speci- 



