288 Mr. A. Adams on the Animal of Umbonium vestiarium. 



scapus pedalis, basi 2 lin. crassus; folia radical ia plurima, rosu- 

 lata, 2^-3^ poll, long., 1 lin. lat. ; folia scapi breviora ; capitu- 

 lum 8 lin. diara. ; corolla 2 lin. long., omnino alba, tubo at- 

 tenuato, palese liberee, lineari-setaceae ; ovaria libera, profunde 

 5-angulata, et, ut in ultima specie, valde hyalina, dentibusque 

 5 acutis coronatis*. 



[To be continued.] 



XXXIX. — On the Animal of Umbonium vestiarium. 

 By Arthur Adams, F.L.S. &c. 



Since writing my notice of the animal of Umbonium giganteum, 

 which I observed at Hakodadi in Japan, I have had an oppor- 

 tunity, in the north of China, among the Mia-tau Islands, at the 

 entrance of the Gulf of Pe-chili, of observing Umbonium vestia- 

 rium, Linn. (Rotella lineolata, Lamk.), in a living state, and have 

 succeeded in procuring a correct figure of the architect of a shell 

 which, like that of Phorus and Terebellum formerly, has long 

 been familiar to naturalists, but the true position of which, in a 

 natural arrangement of Mollusca, has remained doubtful. 



The animal may be found, at low-water spring-tides, in vast 

 numbers covering the sandy patches between the trachytic and 

 basaltic rocks which compose the basis of the islands of this 

 group. Some few individuals, half-covered with sand, may be 

 seen on the surface ; but the majority must be sought for under 

 the surface of the wet sand, by following the traces they leave, 

 They burrow rapidly by means of their broad and flexible foot, 

 which they press downwards, and scoop out a bed for the shell, 

 throwing up the sand from under it. The use of the curious 

 fimbriated funnel-shaped organ formed from or appended to the 

 modified eye-peduncle of the left side is now obvious : it serves as 

 a means of communication between the surrounding water, which 

 fills the cavity in which the Umbonium is lodged, and the gills 

 — ejecting the particles of sand, and performing the part of a 

 true siphon. 



On a level surface the animal marches in a deliberate manner, 

 taking long strides as it seems, the onward movement being 

 effected by alternate lateral undulations of the foot, one -side 

 advancing at a time. As it walks, the caudal extremity moves 

 from side to side in an undulatory manner. The Umbonium is 

 very sensitive to alarm, shrinking at any sudden noise or vibra- 

 tion. When placed on its back, it soon rights itself, by placing 

 its foot under the shell, and will often turn over several times. 



The muzzle is short and rounded, and of a pale brown, the 

 extremity being pellucid, and the margins furnished with ra- 

 * This species is represented in Plate 4/ c. 



