736 REPORT— 1895. 



here, as elsewhere, characteristic of what I have previously termed the ' synaptic 

 phase.' 



The whole course of the spermatogenesis appears to correspond more closely 

 with that of Elasmobranchs than of Mammals, since there appear to be two 

 generations and one division after the synapsis before the spermatozoa are 

 complete. 



As in Elasmobranchs and Mammals, the number of the chromosomes appears to 

 be reduced during the synapsis, and to be then determined for succeeding divi- 

 sions, just as in the case of plants. 



The spermatogenesis of birds supports in every way the conclusion first put 

 forward by 8trasaburger, which is at present gaining ground, namely, that the 

 process of numerical reduction in the chromosomes is not brought about by any 

 division at all, and is similar for both animals and plants. 



5. On the Development of the Teeth in Certain Inseetirora. 

 By M. F. Woodward, Demonstrator of Zoology, R.C.Sci. Lond. 



In the hedgehog the author describes vestigial calcified milk predecessors to 

 the third upper incisor, the lower canine, and the first pre-molar of both upper 

 and lower jaws, and an uncalcified vestige of the milk predecessor of the second 

 lower incisor, thus extending Leche's observations and confirming his later con- 

 clusion that the adult incisors, canines, and pre-molars all belong to the third or 

 replacing tooth series. In addition, a vestigial anterior lower incisor and a third 

 lower pre-molar were observed. Indications of three dentitions are described for 

 the molar series, the molars being referred to the third or replacing dentition. 



The teeth of Gymnura, Sore.r, Talpa, Centetes, and JEricultis are also dealt 

 with, and the following points more especially noted : — 



1. The presence in Gytmiura of five pre-molara in both upper and lower jaws, 

 represented in both dentitions. 



2. Tlie absence of the alleged milk predecessor to the tirst pre-molar of Talpa 

 described by Spence Bate, that tooth being shown to be itself a milk tooth. 



3. The development, in all cases, of the successor to the fourth pre-molar 

 between the ' deciduous pre-molars 3 and 4.' The facts associated with this 

 appear to indicate that the so-called ' deciduous pre-molar 4 ' is a precociously 

 developed molar, and that the tooth which replaces it is a much retarded pre- 

 molar of the milk series. 



Two sets of calcified teeth are shown to be for the greater part developed 

 among Insectivores, and it is characteristic of them that there is a tendency 

 towards reduction of the milk set with early development of the replacing denti- 

 tion, 



6. On the Mammalian Hyoid} By Professor G. B. Howes. 



The author proved from the study of Nasua that the small bone attached to 

 the paroccipital process in Lepus and Trocaria {Hyrax), independently described 

 by Krause and Brandt, is in reality the styloid, and showed that the discovery 

 enables us to recognise two distinct culminating types of modification of the hyoid 

 of mammals, viz. (i.), the protero-stylic, known only in man and the marmosets, 

 and (ii.) the opistho-stylic, known only in the rodents mentioned. Reviewing the 

 subject more generally, he called attention to the presence of a considerable tym- 

 pano-hyal, occupying a novel position, in Choloapus, and he exhibited the hyoid 

 of a young rabbit, the body of which was subdivided by a transverse suture, 

 probably indicative of the original demarcation-line between its two component 

 * copulae.' A classification of the types of mammalian hyoid was submitted. 



' Paper will be published in Jour. Anat. and Phys., Jan., 1896. 



