Mr. Broderip and Mr. (i. B. Sowcrby ow Mollusca. 47 



Having thus endeavoured to shew the necessity of establishing a new 

 genus at least, if not a new family, let us proceed to describe the animal. 

 There were four specimens, one of which was sacrificed to the inquiry ; 

 but decomposition \vas so far advanced that the ovaries and other viscera 

 were nearly reduced to a shapeless pulp, and we could only trace those 

 parts of the internal structure, which we proceed to lay before our 

 readers.* The mantle appears to adhere only to the orifices, each of 

 which consists of six triangular valvules. Each valvule is furnished 

 with a set of muscular fibres, adhering at one end to the inner surface of 

 the tunic (not of the mantle) and at the other extremity to a small pa- 

 pillary process on the valvule. These muscles appear to be the agents for 

 opening and shutting the valvules. Besides this set of muscular fibres 

 and within them there is another set, which passes laterally from one 

 papilla to another, forming a sphincter, the base of which is hexagonal. 

 [Tab. III. fig. 6.] There are other strong subcutaneous muscular fibres, 

 passing from the edge of the upper part of the tunic to that of the lower, 

 and also from the edge of each of the coriaceous plates which form the 

 upper surface. These appear to be intended to give the animal the power 

 of dilatation and contraction. Externally, the animal is of an oblong 

 cup-shape, adhering by coriaceous processes from the lower part of the 

 cup. The upper surface, which is flat, consists of eight coriaceous, 

 somewhat horny, angular plates. One of these is placed between the 

 two orifices, and, in four specimens which were examined, this was of an 

 hexagonal shape, the sides coming in contact with the orificial valvules 

 being lunated. The plates are so disposed that the branchial orifice is 

 surrounded by three plates, and the anal orifice by four, besides that 

 which is intermediate and abuts upon both. The three plates near the 

 branchial orifice are much larger than the four which are near to the anal 

 orifice. Each of the plates is marked with three or four elevated striae, 

 parallel to the sides of the plate, and near to them, leaving an area in 



• The decomposition, which prevented any thing like an accurate demon- 

 stration of the ovaries and other viscera, was, apparently, occasioned by the 

 spirit in which the specimen was preserved not having sufficiently penetrated 

 to the internal parts. This is mentioned, in order to draw the attention of col- 

 lectors to the necessity of puncturing the external integuments, muscular coats, 

 &c. of such animals as are plunged entire into spirit, in order that it may 

 reach and preserve the viscera. 



