POLYCLAD FLATWORMS — ^HYMAN 575 



the color is light gray flushed with yellowish brown. Along the center 

 of the median ridge there runs a narrow light line flanked on each 

 side by yellowish brown. The yellowish brown color deepens near 

 the margin which is edged by a very narrow light line. The tentacles 

 appear brown edged with a light margin. There is some suspicion 

 in my mind that the tawny brown color may be caused, at least in 

 part, by the presence of ripe eggs in the interior. 



Differential diagnosis: The worm is characterized by the large 

 size, elongated shape, small compact pharynx, and color pattern. 



Holotype: USNM 28656, in alcohol. 



Paeudoceros fuscogriseus, new species 



Figure 10c,d 



Material: Two specimens were collected by the Stanford team in 

 eel grass in the channel between Peliliu and Ngedebus, Palau Islands, 

 Sta. 37, July 25, 1955. 



General characters: The worms are of moderate size and general 

 oval form, tapering posteriorly to a pointed tail (fig. 10c). The larger 

 specimen measured, preserved, 23 by 10 mm., the smaller one, 16 by 

 8 mm. Both worms were bent in the pharyngeal region and ruptured 

 there when straightened out, hence it did not appear profitable to 

 section the copulatory region of one of them as this would probably 

 be involved in the rupture. The anterior end of the larger specimen 

 while cleared is shown in figure 10c?. The tentacles, much distorted 

 by preservation, are provided with numerous eyes and well behind 

 them is seen the group of cerebral eyes, consisting of two oval clusters. 

 The relatively large ruflled pharynx has the butterfly shape already 

 mentioned in connection with P. ferrugineus. The single male pore 

 is embraced by the posterior pharyngeal folds and shortly behind it 

 is seen the female gonopore. The sucker of the larger worm is located 

 at about 12 mm. from the anterior end. The usual middorsal ridge 

 seen in pseudocerids is indistinct here. The main intestine could 

 be seen in the posterior part of the worm. 



Unfortunately, no information is available about the color in life 

 but probably it was the same as in the preserved worms. They are 

 dusky grayish brown in color with the anterior central part of a 

 somewhat lighter shade. The extent of the light region is indicated 

 b}^ the dotted line m figure 10c. The line passes along the edge of the 

 pharynx, slightly behind the sucker, and diverges at the anterior 

 margin. The boundary between the lighter and darker shades of 

 grayish brown is quite sharp. 



Differential diagnosis: This species lacks very definite charac- 

 teristics but the combination of paired cerebral eye clusters, large 



472590—59 3 



