blance between the animal of the Gaper-shell and some of the Ascidians is evident at a glance; and indeed, as Messrs. Forbes and Hanley well remark, the aspect of a living Gaper-shell is almost exactly that of an elongated Cynthia, against whose sides two plates of shell have been pressed.
The shell of the Blunt Gaper is variable in form, being so frequently deformed that a large and undistorted specimen is not very often seen in the cabinets of ordinary collectors.
At Plate II., fig. 5, is drawn a figure of the common Basket-shell (Corbula nucleus), which is so plentiful on our coasts, but which is seldom picked up on the shore. It affords an excellent type of the family to which it belongs, the various distinguishing points being very strongly marked. The two valves are exceedingly unequal, the right being large, deep, rounded, and completely overlapping the left valve, which is flat and comparatively small. It is nearly covered with a membrane like that of the Gaper-shell, while the other valve is bare. The beaks are boldly marked, as may be seen by reference to the illustration, which shows the left valve as it appears when partially overlapped by the other. At page 25, fig. 3, is drawn the inside of the shells, showing the curved tooth of the right valve, and the corresponding hollow and cartilage in the left valve. This is a little shell, seldom exceeding half an inch in length.
Another shell, belonging to the same family as the Basket-shell, is drawn at Plate II., fig. 4. As may be seen by reference to the illustration, it is of a very remarkable shape, being prolonged at the hinder end into a sort of tube, and the body of the shell swelling out boldly, so as to make the contrast greater. The valves are covered with a membrane, which is variable in hue, but is generally of a pale fawn colour. The shell itself is very delicate in appearance when the
