Zoological Society. 63 



young ones when, or shortly before, it was killed. The existence 

 of the marsupial bones in the male as well as the female sex in other 

 marsupial animals had already invalidated the above physiological 

 explanation, and it equally opposes the idea of the use of the mar- 

 supial bones, propounded by M. de Blainville, — that they aid in the 

 compression required to expel the embryo. Besides, it is not in the 

 females of those animals which give birth to the smallest young that 

 we should expect to find auxiliary bones for increasing the power of 

 the muscles concerned in parturition. My view of the uses of the 

 marsupial bones, as explained in the ' Philosophical Transactions ' for 

 1834, is, that they relate more immediately to an increase of power 

 in the muscles {cremasteres) which wind round them, than of those 

 implanted in them : and to the extent to which the cartilaginous 

 representatives of the ossa marsupialia in the Thylacine strengthen 

 the pillars of the abdominal ring, they must increase the contractile 

 force of the compressors of the mammary glands and teats, which 

 are situated and surrounded by the cremasteres in the Thylacine, as 

 in other Marsupialia. Nevertheless, the almost obsolete condition of 

 the ossa marsupialia in the Thylacine, and their very various relative 

 sizes in other Marsupialia, are circumstances which seem incompa- 

 tible with the same kind and degree of use in all the species : they 

 are very slender, and not above half an inch in length in the Myr- 

 mecobius, whilst in the Koala they nearly equal the iliac bones in size. 

 The so-called ' pyramidales' muscles, which derive a great proportion 

 of their origin from the ossa marsupialia, bear a direct ratio to 

 those bones in size ; and an attentive observation of the habits and 

 modes of locomotion of the different marsupial species is still want- 

 ing for a complete elucidation of the function of the marsupial bones. 

 It is important to the palaeontologist that the cartilaginous condition 

 of the marsupial bones in the Thylacine should be borne in mind in 

 regard to the evidences of the marsupial order that may be yielded 

 by fossil remains : the fossil pelvis of the Thylacine, for example, 

 had that species been long ago, as it soon is likely to be, extinct, 

 would never have afforded the triumphant evidence to which Cuvier 

 appealed in demonstration of the Didelphys of the gypsum quarries 

 at Montmartre ; yet the Thylacine would not therefore have been 

 less essentially a marsupial animal. This may teach us to pause 

 before drawing a conclusion against the marsupial character of the 

 small Stonesfield mammalia, if their pelves should ever be found 

 without trace of the ossa marsupialia. 



" Descriptions of new Shells, collected during the voyage of the 

 Sulphur, and in Mr. Cuming's late visit to the Philippines," by Mr. 

 Hinds. 



Abstract of the accompanying descriptions of shells : — 

 The number of well- authenticated species of Terebra hitherto on 

 record is about sixty. In the present paper exactly fifty more are 

 added, all of which are presumed to have been hitherto unrecorded. 

 Of this number sixteen are from the Indian seas, six are from the 

 African seas, twelve are from the American seas, and five are from 



