ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 135 



blind cave newt {Typhlotriton spelseus), but it is also absent in adults of 

 Salamandra maculosa, S. atra, and Salamandrina perspicillata, where the 

 eye is not rudimentary. In cases where the larva- are aquatic and the 

 adults terrestrial {Salamandra, Salamandrina, etc.), the scleral cartilage 

 is present in the larval stage (so far as is known) and absent in the 

 adults. 



Minute Structure of Penis and Glans in Lemurs.* — Ed. Retterer 

 and H. Neuville, continuing their comparative study of the external 

 male genitalia, deal with the penis of the Aye-Aye, Lemur catla, 

 L.mongoz, and Galago. The glans is free in Aye- Aye and Lemur ; in 

 Galago it is united by a frenum to the prepuce. There is a bone in the 

 penis or the glans in the Aye-Aye and Lemurs ; there is none in Galago 

 where the corpora cavernosa are adipose as in many Feline animals. 

 There is little foundation for the view that the glans is a swelling or 

 distal expansion of the corpus spongiosum. Three-fourths or five-sixths 

 of the glans (the pubic or dorsal portion) represent the distal end of the 

 corpora cavernosa and their integumentary envelope. The remainder 

 (the ventral or rectal portion) corresponds to the corpus spongiosum of 

 the urethra, which itself results from a fusion of the two folds of the 

 corpora cavernosa. 



c. General. 



Distribution and the Origin of Species. f — Asa C. Chandler has 

 enquired into the relation between the extent of distribution and 

 "speciation." His facts relate to mammals, birds, reptiles, amphibians, 

 insects, and amphipods. As the range of a group of animals is extended, 

 the species increase out of proportion to the genera, the genera out of 

 proportion to. the families, and the families out of proportion to the 

 orders. Allowing for explicable exceptions, the increase in number of 

 lower systematic groups out of proportion to increase of higher systematic 

 groups as the area considered is enlarged, is a remarkably constant and 

 widespread phenomenon. The author shows how the phenomenon may 

 be theoretically explained in terms of isolation, the time element, and 

 the causes of specific and generic transformation. 



Scales of Heterodontus francisci.+ — J. Frank Daniel has made a 

 minute study of the scales of this Californian shark. The ventrals may 

 be distinguished from the dorsals. The ventrals on side view are not 

 unlike helmets. Various types occur, such as the stomodaeal denticles. 

 A dorsal scale, seen from above, presents the appearance of a Greek 

 cross, upon which an unusually high and sharp-pointed spine arises. 

 Various types occur, such as the supra-orbitals and the anchor scales at 

 the base of the pelvic fins and behind the cloaca. The study of transi- 

 tion areas leads to the conclusion that the dorsal and ventral scales 

 represent distinct types with structural differences dependent largely on 

 the location of the scale. In other words, an indifferent scale may 



* C.$. Soc. Biol. Paris, Ixxvii. (1914) pp. 509-12. 



t Amer. Naturalist, xlviii. (1914) pp. 129-60. 



J Univ. California Publications (Zool.) xiii. (1914) pp. 147-66 (2 pis. and 4 figs.). 



