A. M Verrill — Marine Planarians of Neio England. 501 



figured by Mr. A. Agassiz,t under the name oi Flanarla angulata, 

 did not belong to this species, for he stated that the eggs found 

 by him were in " a string of eggs, mistaken at first for those of 

 some naked mollusk," which is the case with the eggs of many 

 Polycladidea, but not with those of this genus. The embryos ob- 

 served by him were not sufiiiciently advanced for identification, but 

 the structure of the stomach and its branches, so far as developed, 

 agrees better with one of the Polycladidea than with that of any 

 of the Tricladidea. The embryos of BdeUoura before leaving the 

 capsules usually have the three main divisions of the stomach clearly 

 visible, as well as the two eyes.* 



This is a true parasite. It sucks the blood of its host and destroys 

 the substance of the gills. When large numbers are present the gills 

 of the Limxdtis are often extensively damaged in this way. 



It is gregarious in its habits. Large clusters of the adults are 

 often found grouped together on the joints of the legs as well as 

 on the gills of Limuhis. Even in confinement they preserve the 

 same habit, adhering to the glass in large groups. When disturbed 

 they often swim away with undulatory motions, like certain leeches. 



This species is particularly favorable for anatomical studies, for 

 the tissues are well differentiated and the various organs are more 

 distinct than in many other allied planarians. The small amount 

 of pigment in the integument is also favorable, especially when 

 examined in the living or fresh condition. It is also very tenacious 

 of life, for it will live for a long time without food in a very small 

 amount of sea- water. 



Some of the principal anatomical characters that can be made out 

 with living specimens are represented on plate xliv, figs. 8, 8«. 

 Figure 8 shows a ventral view of the entire worm only slightly com- 

 pressed, and figure 8a shows the posterior portion of another indi- 

 vidual more strongly compressed, so as to show the reproductive 

 organs better, but in this figure the intestinal branches (^') are so 

 much compressed that they appear unnaturally broad and swollen, 

 while the outline of the posterior sucker is obscured, for the same 

 reason. In this figure the nervous system is omitted. 



The lateral gastric branches (left unshaded in fig. 8) in adult 

 specimens are very numerous, ten to twelve arising from each side 

 of the anterior trunk or median division of the stomach (^), while 



* Several writers, have carelessly referred to the embryonic forms, described by Mr. 

 Agassiz, as the young of this species, although the true egg-capsules of the latter 

 have long been known. 



f .Annals Lyceum Nat. Hist., New York, vol. viii, pp. 306-309. 1860. 



