220 F. W. GAMBLE, B.SC. 



Distribution. — Naples (v. Graff), where it is the most abundant 

 Rhabdocoele ; Trieste (v. Graff and Bohmig) ; Messina (v. Graff). 



41. Plagiostoma ochroleucum, v. Graff. 



Length 5*5 mm. Colour whitish yellow. Mouth sub-terminal. 

 Pharynx very small, beneath and in front of the brain. Eemaining 

 anatomy similar to PI. Girardi. 



Habitat. — 1£ fms, among Laminaria, Millport (v. Graff). 



Genus 18.— Vorticbros, 0. Schmidt (28), 1852. 

 Plagiostomince with two tentacles at the anterior end. 



42. Vorticbros auriculatum (0. F. Miiller, 4). 



Length 1*5 mm. Body produced anteriorly into a pair of long 

 tentacles. Behind the eyes it is slightly constricted, and then expands 

 towards the middle, tapering behind to a fine point. The tentacles are 

 not often seen fully extended. At the slightest alarm they can be 

 completely withdrawn, and the animal may continue to swim about in 

 this condition. The colour is variable, but usually consists of a broad 

 band of dark carmine reticular pigment on the upper surface, leaving 

 the side margins free, and continued on to the tentacles. The anatomy 

 differs in no important particulars from that of the genus Plagiostoma. 



Habitat. — Among Ulva and other littoral weeds, Plymouth ; Port 

 Erin, Isle of Man (F. W. G.) ; Millport (v. Graff). 



Distribution. — Naples, Trieste, Messina (v. Graff), Wimmereux 

 (Hallez), Norwegian coast (Miiller). 



43. Vorticeros luteum, v. Graif (53). 



1852. Voeticeros pulchellum, 0. Schmidt (28). 



1879. „ „ var. luteum, Hallez (50). 



This species, established by v. Graff for the reception of a large 

 specimen (8 mm. long), is distinguished from the preceding by its 

 stouter appearance and uniform yellow colour. On two occasions at 

 Plymouth an example measuring 2 - 5 mm. in length was taken. One 

 was found among Bugula turbinata from 7 fms., the other among 

 littoral weeds at a low spring-tide. 



Distribution. — Wimmereux (Hallez), Naples (v. Graff). 



