62 SYSTEMATIC ARRANGEMENT 



a conspicuous mentum in front. Tongue unarmed. A single bran- 

 chial plume. 



1. S. ovoidea, n. s. t. 126 a. f. 3 ; Adams, Gen. Moll. t. 25. f. 4. 



2. S. , n. s. t. 126. f. 5. 



3. S. Turtoni, Forbes 8f Hartley, B. M. t. O.O. f. 5. 



In the original description of the animal the contracted foot 

 appears to have been described as the mantle partly covering the 

 shell. — Soiv. Genera, t. 



The animal of Stylina Turtoni is white, with a rather large foot, 

 without any operculum, a round head with two cylindrical tentacles, 

 and minute eyes at the external or posterior base. No portion of 

 the shell was covered with the fleshy part, but I am not certain that 

 in a state of vigour the animal has no power of extending some part 

 of the mantle or foot over it. The animal has much the appearance 

 of an Eulima. It has no large anterior disk, like Natica. The 

 remains of the animal examined under the microscope did not show 

 any denticulated tongue. — Alder, Cat. Moll. Newc. 46. 



Otolites of Stylina Turtoni circular, with a central dot. Gills ? 

 a single series of triangular lobes. No lingual band visible in the two 

 specimens I have examined. Mouth breaks up into squarish angular 

 fragments, not crystalline, perhaps horny. — Alder, MSS. 



Like Eulima the shell is often curved. Some species appear to 

 live attached to the spines of Echini, while others are only found 

 imbedded in the substance of starfish. 



The Stylina stylifera of Macgillivray is described from the shell 

 of a young exotic Bulimus. — Jeffreys. 



12. Entoconcha. 



" Shell obovate, smooth ; whorls very rapidly enlarging ; spire 

 short, very blunt, tip not produced ; aperture transverse, semilunar, 

 angulated above, rounded beneath, margin disunited ; pillar edge 

 straight ; mouth nearly as long as broad. Operculum not spiral." 



1. E. mirabilis, J. Mailer, Berlin Acad. 1852 ; Zool. Arch. 1853, 

 102. 



Living in Synapta digitata. 



Fam. XXV. ARCIIITECTOMIDiE. 



Shell conical, depressed, having an umbilicated axis. Foot mode- 

 rate, for walking. Tentacula near together, nearly united at their 

 base, over the retractile trunk, grooved beneath. Gill-cavity divided 

 by a longitudinal fold. 



1. Architectoma. 



Shell conical ; whorls few, square. Operculum ovate, flat, few- 

 whorled.— Adams, Gen. Moll. t. 25. f. 6 a, b. 



