482 F. W. GAMBLE. 



produced into a fine flagellura in front and behind. Eyes 

 absent. For further details and figures see v. Graflf, 'Monogr.,' 

 p. 404j and pi. xix, figs. 15 — 17. 



Habitat. — A specimen at Millport in a tide-pool (v. GraflF). 



V. GraflP described this form as the only blind Plagiostomid. 

 I have, however, found a probably new species of Plagiostoma 

 in which the eyes were wanting. 



Genus 20. — Allostoma, van Beneden (33). 



AUostominae in which the "circular furrow" at 

 the level of the brain is provided with long 

 cilia. 



47. Allostoma pallidum, van Beneden (33). 



Length 2 mm. Body cylindrical, tapering slightly to- 

 wards each extremity. The anterior sixth is sharply separated 

 from the rest of the body by a transverse marking, the nature 

 of which is not quite clear. It is probably due to the ciliated 

 " circular furrow." Colour yellowish white. The epidermis 

 contains numerous pseudo-rhabdites. Considering rhabdites 

 as a condensed glandular secretion, pseudo-rhabdites are 

 intermediate between the amorphous secretion and rhabdites. 

 The mouth is posterior; the pharynx short, leading into 

 an extensive gut. v. Graff has described the genital organs 

 fully. Testes surround the brain. Vasa deferentia 

 convey the sperm in balls to the base of a pyriform penis, in 

 front of which lie the ovaries. The oviducts unite and open 

 through the subtermiual genital pore. Yolk-glands lateral, 

 lobed. (See v. Graff, 'Monogr.,' pi. xix, figs. 12—14.) 



Habitat.— Millport (v. Graff). 



Distribution. — Ostende (van Beneden, v. Gra6F). 



Van Beneden (33) has described the oval egg-capsules, which 

 are very small, and extruded one at a time. The young when 



