170 Mr. H. N. Moseley on the Anatomy and [Feb. 20, 



Lists are given of all the known species of Bipalium and Ehynchodemus, 

 and also a map to show the distribution of Bipalium in space. 



With regard to the habits of Bipalium, the most interesting facts 

 noted are that these animals use a thread of their body-slime for 

 suspension in air, as aquatic Planarians were observed to do for their 

 suspension in water by Sir J. Dalyell, and the cellar-slug does for its 

 suspension in air. The projection of small portions of the anterior 

 margin of the head in the form of tentacles, originally observed by M. 

 Humbert, becomes interesting in connexion with the discovery of a row 

 of papilla) and ciliated pits in that region. The anatomy of the Planarians 

 was studied by means of vertical and longitudinal sections from hardened 

 specimens. The skin in Bipalium and Rhynchodemus closely conforms to 

 the Planarian type, but is more perfectly differentiated histologically 

 than in aquatic species, and approaches that of the leech in the distribu- 

 tion, colour, and structure of its pigment, and especially in the arrange- 

 ment of the glandular system. The superficial and deep glandular 

 system of the leech are both here represented. In B. Ceres peculiar 

 glandular structures exist, which may foreshadow the segmental organs of 

 Annelids, it being remembered that these segmental organs are solid in an 

 early stage of development. Rod-like bodies (Stabchen or stabchenfor- 

 mige Korper) are present in abundance, though, singularly enough, Max 

 Schultze failed to find any in Geoplana. These rod-like bodies are pro- 

 bably homologous with the nail-like bodies of JSTemertines ; and it is pos- 

 sible that the setae of Annelids are modifications of them. No light is 

 thrown by the structure of these bodies in Bipalium on the question 

 whether they are homologous with the urticating organs of Coelenterata. 



The muscular arrangement in Bipalium, which is very complex, throws 

 great light on the homologies between the muscular layers of Turhellaria 

 and those of other Vermes. It is commonly said that whilst in all other 

 Vermes the external muscular layer is circular, and the longitudinal internal, 

 in Turbellarians the reverse is the case. A wide gulf . is thus apparently 

 placed between these groups. In Bipalium there is an external circular 

 muscular coat, which even presents the same imbricated structure which is 

 found in it in leeches and other worms. In Dendroccelum lacteum there 

 is also an external circular coat. In cases where a distinct external 

 circular muscular coat is absent, it is represented by a thick membrane, 

 which is very probably contractile. The question resolves itself simply 

 into a more or less perfect fibrillar differentiation of that membrane. All 

 Turbellarians are built on the same essential type, as regards muscular 

 arrangement, as are other worms. The general muscular arrangements 

 in the bodies of the Bipalium and Rhynchodemus have become much 

 modified from those of flat Planarians by the pinching together and 

 condensation of the body, but they are nevertheless referable to the 

 same type. 



The digestive tract consists of three tubes (one anterior, two posterior), 



