456 Zoological Society. 



Thus, Plac. Cumingii, to a casual observer, looks like one of the 

 plicated Oi/sters ; Plac. rudis greatly resembles the common Oyster, 

 Ostrea edulis ; and Plac. echinata wears something of the appear- 

 ance of some of the short-spined Spondyli. — W. J. B. 



Besides the species above recorded Mr. G. B. Sowerby has kindly 

 furnished me with an odd valve of a large species from Luconia, 

 beautifully iridescent internally : but as it is believed that this is 

 identical with the fine shell sold by him to the British Museum, I 

 leave the description of it to the officers of that institution, in whose 

 province it is, and who are so fully capable of doing it justice. 



This genus, then, appears to be widely diffused. Mr.G. B. Sow- 

 erby has some other odd valves which may prove new. I possess 

 two or three specimens adhering to Spondyli from an unknown lo- 

 cality ; but they appear to be young, and, though I am inclined to 

 think that there is among them a new species, I wait for further 

 information before I venture to characterize it. — W. J. B. 



Mr. Owen read the following Notes on the Anatomy of the pur- 

 ple-crested Touraco, Corythaix porphyreolopha, Vig. 



"In commencing the anatomical examination of this Bird, my at- 

 tention was first directed to the form of the tongue. This was large, 

 and not confined to the posterior region of the mouth, but ex- 

 tended to the end of the lower mandible : its apex was beset with 

 a few small horny bristles directed forwards, as in the Toucans, 

 Rhamphastos, Linn., but much less produced than in those birds. 

 It is probable that the ripeness of fruit on which these birds feed is 

 tested by these yielding processes. The base of the tongue was, as 

 usual, beset with retroverted papilla;, and elevated into a distinct 

 ridge, serving, as in many of the cold-blooded ovipara, as an epi- 

 glottis. The interspace between this ridge and the laryngeal aper- 

 ture was very glandular. That aperture was simple and terminated 

 posteriorly by two retroverted spines; so that it is defended in some 

 decree against regurgitated food as well as from that which is swal- 

 lowed. 



" The oesophagus is continued down to the stomach of uniform 

 ample width ( its diameter beingirds of an inch) without any dilatation 

 or invluvies, as in the true Rasorial birds. Its termination for about 

 ^ths'of an inch is occupied by the zone of gastric glands, forming 

 the proventriculus, which does not deviate in capacity or course from 

 the rest of the gullet. The gastric follicles are simple, elongated 

 and rather flattened. The gizzard is small and weak in its parietes, 

 resembling that of the Toucan. Its length is 1 inch 4 lines; its 

 greatest diameter 10 lines. The lateral tendons are distinct, and 

 the narrower portion beyond the pylorus has the strongest muscu- 

 lar coat, which, however, does not exceed at this part -j-rd of a line 

 in thickness. 



" The capacity of a gizzard of this structure is obviously one 

 reason why a crop or reservoir is not required: where the muscu- 

 lar parietes encroach upon the digestive cavity, so as only to allow 

 small portions of food to enter at a time for the purpose of under- 

 going trituration, then a crop is as necessary to the gizzard as the 

 hopper to a mill. It is also required in some of the most carni- 



