BRITISH MARINE TURBELLARIA. 211 



Testes paired, compact. Mouth ventral, usually anterior. Pharynx 

 dolioform* Copulatory organ oj various shapes (v. Graff, ' Monogr.,' 

 p. 342). 



Subfamily EuvorticiNjE. 



Pharynx and brain well developed. Germaria small. Body-cavity 

 extensive. Parenchyma small in amount. Free-living, 



Genus 16. — Provortex, v, Graff. 



Euvorticinoe ivith two germaria and two distinct, elongate, unbranched 

 vitellaria. Testes rounded. Pharynx dolioform. Mouth in the 

 anterior third, Vesicula seminalis enclosed by the penis. Copulatory 

 organ traversed by the spermatozoa (v. Graff, ibid., p. 344). 



28. Provortex Balticus (Schultze, 27). 



Length - 6 — 1 mm. Body cylindrical, truncate in front, the angles 

 produced into blunt processes, widening towards the middle and 

 tapering behind to a long " tail." Colour brown, due to scattered 

 reticular pigment. Epidermis containing flagella interspersed between 

 the cilia. Pharynx provided with a distinct seam, into which the 

 pharyngeal retractor muscles are inserted. From the extended 

 observations of von Graff and Jensen it appears that this species is 

 divisible into macro- and micro-pharyngeal varieties. Eyes paired, 

 reniform. The genital aperture is ventral, at the base of the " tail." 

 The testes lie far forward at the sides of the pharynx, and lead into 

 paired vasa deferentia. These unite along with the " granule secretion " 

 in the base of the copulatory organ. This organ is slightly variable in 

 shape, and consists of a wide, cylindrical, tubular basal portion, 

 opening through a narrow transverse slit, one edge of which is 

 continued parallel to the axis of the cylinder, and then bends sharply 

 at right angles. Germ and yolk-glands lateral ; near their point of 

 union is a curved spermotheca. 



Habitat. — This very active tiny animal occurred abundantly among 

 Laminaria and also in brackish water at Millport (v. Gran). Abundant 



* i. e. barrel-shaped. The term is, however, used in a technical sense, 

 including certain structural peculiarities (see v. Graff, * Monographie,' 

 pp. 83—4). 



