ON STYLOCHUS PELAGICUS. 27 



the tissue over the body, besides appearing in a riper form 

 in the lateral organs. Eut these lateral organs are surely to 

 be regarded as reservoirs to which the ova pass from the 

 various cells as they become ripe, where they receive per- 

 haps addition of yelk, and where they are stored until 

 fecundation is effected. They thus correspond to the lower 

 and central parts of the ovaries of Bipalium and other forms 

 in which the ripe ova are to be found awaiting passage to 

 the uterus, whilst the upper parts are filled with ova in all 

 stages of development. 



The exact mode of connection of these lateral organs with 

 the uterus was not observed. The organs were also ob- 

 served in only one specimen out of the four examined. 

 They were not present in the one figured by means of the 

 camera lucida, fig. 9. It is probable that the male and 

 female elements reach maturity at different periods in each 

 individual, and that the one specimen had the female organs 

 in the highest activity. 



A very young specimen, S mm. in length, was obtained. 

 The pharynx was much larger in proportion to the body 

 than it is in the adult, and is more cylindrical in form with 

 fewer folds. The branches of the intestine were fully 

 developed, as were also the cephalic ganglia and eyes. 

 The ganglia especially being of their full size and thus ap- 

 pearing out of proportion to the body, as is the case in so 

 many other animals in the young condition. And as they 

 are figured by Keferstein in the young of Leptoplana tre- 

 mellaris (Keferstein 1. c. Taf. iii, figs. ^0, 21). 



Keferstein folloAved his young planarians only until they 

 were 6 mm. in length. He remarks that they until then 

 showed no trace of generative organs. In the young Sty- 

 lochus the organs were not at all formed, but the area to be 

 occupied by them was plainly defined and occupied by a 

 mass of tissue, denser than that of the surrounding region, 

 evidently destined to their formation. 



Pelagic Planarian, sp. (?) 



Two specimens of a pelagic Planaria Avere obtained by 

 the towing-net in lat. 2° 55' N., long. 124° 53' E., about 

 thirty-five miles west-north-west of Siao Talautse Islands, on 

 October 20th, 1874. Both specimens were very small, 

 measuring only about 3 mm. in length. They were evi- 

 dently very young, having as yet no trace of generative 

 organs, and the tissues not yet well defined. 



The body (Plate III, fig. 5) was ovoid in form, and com- 



