b ON A NEW SPECIES OF ENTEROPNEUSTA, 



as yet in doubt. The large female with its attendant small males 

 is usually found in a very prominent tubular enlargment of a part 

 of the free edge of one of the genital wings. 



Anatomy. 



Proboscis : The epidermis of the proboscis (fig. 5, e^;.) is some- 

 w^iat thicker than in the case of Pt. minuta measuring '11 mm. 

 It is separated from the underlying musculature by the limiting 

 membrane, composed of two layers, the outer attached to the 

 nerve fibre layer of the epidermis, the inner to the circular 

 muscular layer. Between these two layers run the capillaries of 

 the vascular net of the proboscis (fig. 5, cup.). Below the limiting- 

 membrane is the thin layer of circulai- muscle fibres, also some- 

 what thicker than in the case of Pt. minuta, ^'iz., •023 mm. The 

 circular muscular layer gradually l)ecomes thinner towards the 

 neck of the proboscis, and finally thins out altogether. The 

 delicate membrane limiting the circular muscular layer internally 

 can readily be recognised especially in horizontal sections. On 

 the inner side of the membrane, and at a little distance from it, 

 there is an irregular cell layer, the nuclei of which are very 

 distinct in h^ematoxylin preparations. 



From the outer side of this limiting membrane there pass 

 through the circular muscular la3^er numerous fine fibres to the 

 inner layer of the limiting membrane of the proboscis, while on 

 its inner side the fibres of the longitudinal musculature are 

 inserted. 



Tlie fibres of the longitudinal musculature are related in their 

 mode of origin from the prol^oscis base and in their course from 

 there exactly as in Pt. minuta, and they show^ the same separation 

 in preserved specimens into radial masses (fig. 5, Im.). The 

 muscle fibres are embedded in a very fine connective tissue which 

 anterior to the j^roboscis organs occupies the central region of the 

 proboscis, muscle fibres being there absent. The connective tissue 

 here presents a spongy appearance with a few very small nuclei 

 .situated in the course of the connecting strands or in the angles 

 between the meshes. The splanchnic epithelium of the proboscis 



