ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 639 



a continuous metallic-like croak, while the female is perfectly mute. 

 The eggs arc extruded and fertilised one at a time, and are placed each 

 on a leaf, to which their sticky surface causes them to adhere. Some 

 400-500 cgas were laid, and hatching occurred 30-3(5 hours after ovi- 

 position. The animals bred in a water-lily tank of a temperature of 

 22°-2'±° C. at the end of February, instead of in August, the breeding- 

 season at the Cape. 



Breeding-habits of Chromis philander.* — N. Abraham has observed 

 the habits in captivity of a Chromid fish, identified by Dr. Giiuther 

 as this species. A male was observed with ova distending the mouth- 

 cavity, and was removed to a separate aquarium. Within the cavity 

 the eggs hatched, and for two weeks the young were observed within 

 it through the transparent integuments. At the end of this time some 

 sixty young were noticed swimming freely in the aquarium, but all 

 returned to the mouth of the parent on any alarm, and were always 

 collected in this way at sundown, being apparently retained within the 

 mouth till morning. This continued for about five days, after which the 

 male ceased to notice the young. 



Algae on Hair of Sloth.f — E. Lydekker discusses the interesting 

 questions connected with the green algae-bearing hair of the two sloths. 

 He points out that in the three-toed sloth the algal cells are lodged in 

 the cracks of the extra-cortex of the hair, while the different species of 

 alga found in the two-toed sloth lives in the furrows present in the 

 cortex, the extra-cortex being absent in this case. There is reason to 

 believe that the two sloths have been independently derived from 

 ground-sloths, which in all probability had unspecialised hair, not 

 capable of lodging algae. It would thus appear that the remarkable 

 habit of having symbiotic algaj on the hairs must have been acquired 

 independently in the two forms. The young in both cases are probably 

 infected by their parents with the algal spores. 



Adaptation in a Deer 4 — R. Lydekker describes a variety of Cervus 

 eldi from Manipur, in which the foot is modified to enable the animals 

 to live on marshy ground. The under surface of the pasterns, instead 

 of being hairy as in the typical form, is horny and hardened, and is 

 practically continuous with the hoof. In walking the foot is bent, and 

 the under surface of the pastern is applied to the ground. This the 

 author regards as a case of incipient reversion to the ancestral planti- 

 grade mode of progression. 



Cerebellum of Scyllium canicula. § — L. Edinger has studied the 

 nerve-tracts and the minute structure of the cerebellum of the dog-fish, 

 and finds that it is essentially only the end-place of the direct sensory 

 tract from the spinal nerves, all other fibres entering it being of re- 

 latively slight importance. 



Superbranchial Organ in Hypophthalmichthys.|| — G. A. Boulcngcr 

 describes a remarkable organ in H. molitrix from China, which is 



* Ann. Nat. Hist., xlvi. (1901) pp. 321-5. 



+ Knowledge, xxiv. (1901) pp. 223-5. X Nature. Ixiv. (1901) p. 257. 



§ Arch. Mikr. Anat., lviii. (1901) pp. G61-7S (2 pis.). 



|| Ann. Nat. Hist., xlv. (1901) pp. 186-8 (1 tig.)- 



