60 



Genus Stilifeh. {Brod.) 



Testa hyalina, tmbinata, apice spirae stilum mentiente. Apertura 

 subovata, superne acuminata. Labrum acutum, sinuatum. 



Pallium crassum, carnosum, cyathiforme, testae anfractus ultiraos 

 obtegens. Protoscis longissima, retiactilis. Tentacula rotunda, crassa, 

 subacuminata, ad basin proboscidis posita. Oculi ad basin tentacu- 

 lorum, sessiles, minimi. Branchice stirps solitaria. 



Animal marinum. 



Stilifek Astericola. Stil.testd subglobosd, diaphand, laclescente; 

 anfractibus ventricosis, longitudinaliter leviter striatis, ultimo 

 viaximo ; apicis anfractibus duobus : long. -iV> lo.t. -^ poll. 

 Hab. ad Insulas Gallapagos, Asterice sotem cutem penetrans. (Lord 

 Hood's Island.) 



The arrival in this country of the shell above recorded, with the soft 

 parts, has afforded data for a generic character indicating a distinct 

 family among the Pectinibranchiata, the form and disposition of whose 

 mantle differs from that of any other genus in the order. This man- 

 tle(which xnStil. 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 3 and from 

 the sm'all basal aperture a retractile pro^o.scis (which when exserted is 

 as long as the whole animal) is protruded. At the base of this pro- 

 boscis are two thick, round, somewhat pointed tentacula; and at the 

 base of them are the eyes or rather ocular specks without pedicles. 

 The bronchia 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, v^'here it becomes attached to the liver, which, in 

 the present species, is of an orange colour. 



Mr. Cuming found this elegant 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 Siarjish, 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 Stiliferi appeared to be in the 

 best health, though there is reason to believe that these Mollusca feed 

 upon the juices of the Starfish. 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 i\\e pelvis. When extracted, the older shells have much 

 the appearance of a milky-clouded glass bubble 3 the younger shells 

 are of an unclouded transparency. 



Dr. Turton, in the second volume of the ' Zoological Journal' 

 (p. 367, pi. xl.), described and figured a shell under the name of Pha- 

 sianclla stylifera, adding that he found a dozen attached to the spines 

 of Echinus esculentus dredged up in Torbay. It is clear that Dr. Tur- 



