376 ROBERT J. TERRY 



independently and unites secondarily with a process (processus 

 alaris) of the margin of the sella turcica. 



Of the many questions yet unanswered regarding the signifi- 

 cance and relations of the ala temporalis, one only will be dis- 

 cussed here. The cat belongs to the type in which the temporal 

 wing is more or less separate from the rest of the cranium, and 

 in which the connection is an indirect one through a processus 

 alaris. The successive stages of development of the ala tempor- 

 aUs in the cat seem to throw some light on the nature of the 

 differences between the temporal wing of the continuous type 

 and that of the separate type. The following discussion deals 

 with this question. 



We may first compare the development of the ala temporalis 

 in the two types, i.e., the one in which the temporal wing is con- 

 tinuous with the rest of the cranium and that in which it is more 

 or less separate. For the first, Talpa may be chosen as an ex- 

 ample; for the second, the cat. The following results have been 

 brought out by Noordenbos in his study of the mole. In embryos 

 of 12-13 mm. three lateral processes at the side of the pole-plate 

 (basisphenoid) are described. With the posterior one of these 

 processes (basicochlear synchondrosis) we are not here concerned. 

 The "intermediate process, knee-formed, extends from the pole- 

 plate in front of, and then bends laterally around, the carotid 

 artery passing backward to join the cochlear capsule. The an- 

 terior process ends free. In embryos of 14 to 17 mm. the latter 

 has grown so as to come into relation with the Gasserian gan- 

 ghon. In still older embryos (17-19 mm.) the anterior limb and 

 knee of the middle process grow out in connection with the an- 

 terior process to reach the under surface of the semilunar ganglion 

 and thus is formed the ala temporalis. "This little plate is 

 connected with the lateral margin of the basisphenoid through 

 the processus anterior and the anterior limb of the processus in- 

 termedius." Noordenbos states that the largest part of the ala 

 temporaUs is contributed by the anterior lateral process of the 

 pole-plate ; a small part arises from the knee of the middle lateral 

 process. Union of the two elements of the ala occurs in embry- 

 os of 20 to 25 mm., but there remains for a long time, a sJnall 



