128 



collected by Mr. Cuming at Lord Hood's Island, one of the Gallapagos, 

 imbedded in the soft parts of a Star Fish, and a species has been recently 

 obtained by Mr. Adams, under precisely similar circumstances, on the 

 coast of Borneo. The Stilifer, though known for more than half a century 

 by a figure of Chemnitz,* was not described by Lamarck, nor is it men- 

 tioned by M. Deshayes in his new edition of that author ; it was, however, 

 known by the name of Phasianella stylifera to Turton, who found a dozen 

 attached to the spines of an Echinus in Torbay ; and Fleming describes it 

 under the head of Velutina, whilst recording his opinion that it might be 

 elevated to the rank of a genus with the appellation of Stylina. Tins 

 name being already in use for a genus of polyps, Mr. Broderip, to whose 

 skilful care Mr. Cuming intrusted the Star Fish collected by him with the 

 mollusk in situ, adopted the title of Stilifer. The description of the 

 animal given by tins accomplished naturalist from the dissections of 

 Professor Owen,t varies materially from that of Mr. Adams published in 

 the Proceedings of the Zoological Society ; the former describes the mantle 

 as being thick, fleshy, and cup-shaped, completely enveloping the last two 

 or three who'rls of the shell ; % tlie latter conceives tins external organ to be 

 the foot, and the mantle to be very small, concealed within the shell, as 

 described at the head of this genus in his own words. || 



As a solitary instance of a mollusk dwelling and propagating within the 

 fleshy substance of another animal, the Stilifer is an object of great 

 interest ;§ the shell is as delicate and transparent as a glass bubble, and 

 it is curious that whilst one species, S. Astericola, should be almost as 



* Helix corallina, Chemn. Conch. Cab. vol.xi. p. 286. pi. 210. f. 1284-5. 



t Conch. Syst. vol. ii. p. 175. pi. 225. f. 8 to 12. 



X This mantle (which ia Stil. Astericola is of a green hue,) is thick, fleshy, and cup-shaped, 

 with a small aperture at its base and a free posterior margin, enveloping the soft parts and the 

 last whorls of the shell, which has thus somewhat the appearance of a small acorn set in its cup. 

 On the ventral aspect of this mantle is the rudiment of a foot ; and from the small basal aperture 

 a retractile proboscis (which when exserted is as long as the whole animal) is protruded. At 

 the base of this proboscis are two thick, round, somewhat pointed tentacula ; and at the base 

 of them are the eyes or rather ocular specks without pedicles. The branchia is placed on a 

 single stem. At the base of the proboscis is a spherical muscular stomach, and the intestine 

 ascends into the spire of the shell, where it becomes attached to the liver, which, in the present 

 species, is of an orange colour. — Pro. Zool. Soc. 



|| Mr. Gray noticed in his ' Synopsis ' that " what has been called the enlarged mantle appears 

 like the foot," and as Mr. Adams' observations are drawn from the living individual, whilst 

 Mr. Broderip's were from a contracted specimen in spirits, it is highly probable that he is right. 



§ Mr. Cuming fouud this elegant little parasite burrowed in different parts of the rays of the 

 oral disk of Asterias Solaris, Gray, where it is almost hidden from sight, so deeply does the 

 animal penetrate into the substance of the Star Fish, in which it makes a comfortable cyst for 

 itself, wherein it most probably turns by the aid of its rudimentary foot. All the specimens 

 infested with Sliliferi appeared to be in the best health, though there is reason to believe that 

 these Mollusca feed upon the juices of the Star Fish. With that instinct of self-preservation 

 imparted to all parasites whose existence depends upon that of their nidus, the Stilifer, like the 

 Ichneumon among insects, appears to avoid the vital parts ; for, in no instance did Mr. Cuming 

 find it imbedded anywhere save in the rays, though some had penetrated at their base and very 

 near the pelvis. When extracted, the older shells have much the appearance of a milky-clouded 

 glass bubble : the younger shells are of an unclouded transparency. — Pro. Zool. Soc. 1S32. 



