1876.] On the Poison-fangs of. Snakes. 259 



To reverse the process it is only necessary to remark that every number 

 is either uneven, or twice an uneven number, or four times an uneven 

 number, or eight times an uneven number, &c, so that every sum of dif- 

 ferent elements can be uniquely reduced to the form 1+3 . a + 5 ./3 + &c. 

 (The practical reduction is very easy, ex. gr. 14 + 12 + 5 + 3 + 2 converts 

 into 7+7 + 3 + 3 + 3 + 3 + 5 + 3 + 1 + 1.) A little consideration shows that 

 no two different partitions of one system can convert into the same par- 

 tition of the other, so that every partition of either system corresponds 

 uniquely to a partition of the other ; and the numbers of partitions in the 

 two systems are thus equal. Several conversions of P(l, 3, 5 . . .)n are 

 given in the Phil. Mag. for April 1875 (S. 4. vol. xlix. pp. 307-311); 

 but when writing that note I failed to obtain the connexion between 

 the partitions into 1, 3, 5 . . . with repetitions and the partitions into 

 1, 2, 3 ... without repetitions. 



II. " On the Development and Succession of the Poison-fangs of 

 Snakes." By Charles S. Tomes, M.A. Communicated by 

 John Tomes, F.R.S. Received December 28, 1875. 



(Abstract.) 



At the conclusion of a paper upon the development of the teeth of 

 Ophidia, published in the first part of the Philosophical Transactions 

 for 1875, I noted that there were peculiarities, which I had not then 

 been able to understand, in the succession and the development of the 

 poison-fangs. Having reviewed the literature of the subject in that and 

 in a preceding paper on the development of Amphibian teeth, I will pass 

 at once to the description of the special features which distinguish the 

 development of poison-fangs. Poisonous snakes are divided into two 

 groups — those which have a shortened movable maxillary bone, which 

 carries the poison-fang and another tooth ; and those which have the 

 maxillary bone longer, immovable, and often carrying other teeth behind 

 the poison-fang. 



In the former, or viperine poisonous snakes, the poison-fang is very 

 long, and, when out of use, lies recumbent ; in the latter, or colubrine 

 poisonous snakes, it is, from the maxillary bone being fixed, constantly 

 erect (Grunther's ' Reptiles of British India,' p. 165). 



As fresh specimens are indispensable for a complete investigation of 

 developmental peculiarities, I have only been able to examine one of the 

 colubrine group, viz. the Indian cobra. 



Of it one may say, roughly speaking, that the poison-fangs are deve- 

 loped just like any other Ophidian teeth, for a description of which I must 

 refer to my former paper, save only that the tooth-germs are necessarily 

 individually modified so as to produce the characteristic canaliculated 

 poison-tooth. 



