442 RECORD OF CURRENT RESEARCHES RELATING TO 



anterior and a narrow tail-like posterior region, these two being 

 pretty distinctly marked off from one another. The cilia of the 

 integument may be seen distinctly to exhibit their movement along 

 parallel longitudinal lines ; owing, perhaps, to its parasitic habits, the 

 creature is not provided with those rods which have been called 

 nematocysts or sagittocysts. The dermo-muscular layer consists of 

 a layer of external circular, and of another of internal longitudinal 

 muscles, and is separated by a basal membrane or protoplasmic layer 

 from the epidermis. 



The subjacent connective tissue is remarkable for only consisting 

 of very large cells, applied directly to one another, without the 

 intermediation of the slightest amount of fibrous or reticular tissue ; 

 the cells are of some size, and their membrane is very thick. As there 

 is no differentiated enteric tract it is, of course, difficult to say where 

 the connective tissue ends and the enteron begins ; large as the 

 connective-tissue cells are, their nucleus is exceedingly small ; and as 

 it colours not at all, or only at points, it is very difficult to see. 

 Connected with this system there are a number of small spindle- 

 shaped or branched cells, which lie just within the musculature, 

 together with another system of subcutaneous branched and ana- 

 stomosing cells, which have a plexiform arrangement, and which may 

 be easily taken for nerves. It was not possible to demonstrate the 

 existence of any water-vascular system. 



The nervous system is well developed, its central portion being 

 placed anteriorly, both above and below the oesophagus. The central 

 portion is composed of a fibrous mass, round which there are set the 

 small ganglion cells. The cerebral mass gives off anterioz'ly a number 

 of fibres, which unite here and there into small ganglionic masses, 

 and so get, lying as they do just below the integument, to have very 

 much the appearance of the subcutaneous connective plexus, already 

 referred to. The longitudinal lateral trunks, which are often so 

 well-developed in other Turbellaria, are here feebly represented. 

 There is reason to suspect, but there is not yet evidence to prove, the 

 presence of an oesophageal nerve-ring. A distinct optic nerve was seen 

 to pass to the eye, which consisted of a large dark mass of pigment 

 with a large lens. No auditory organs were detected. The size of 

 the cerebral mass is very remarkable, a transverse section taken 

 though the region of the body in which it is placed being almost 

 completely occupied by it. 



The enteric tract consists of a well-developed pharynx, and a 

 saccular aproctous-^intestine, which is, as a rule, devoid of processes. 

 The pharynx communicates directly with the mouth, an arrangement not 

 known in any other Turbellarian, in which it is always placed in a sac ; 

 the mouth, which is nearly round and capable of lively swallowing 

 movements, is placed on the ventral side, a little posteriorly to the 

 anterior end of the body. Just below the epithelium of the pharynx 

 there is a circular layer of muscular fibres, which is separated from the 

 outer circular layer by a large mass of radial muscles and connective- 

 tissue cells ; at the anterior end the circular muscles unite to form a 

 powerful sphincter. The enteric tract presents some interesting 



