174 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Monstrosity of Bladder in Frog.* — "W. Woodland reports a case in 

 which the left lobe of the bladder of Rana temporaria, was proximal ly 

 stretched to form a thin tube, which, running anteriorly in the body- 

 cavity, perforated the muscular portion of the ventral body-wall, and 

 expanded distally into a spherical sac, lying external to the muscles and 

 in the median ventral lymph-sinus. Permanently imprisoned in the distal 

 sac was a full-grown specimen of the usual parasite, Polystomum inte- 

 ger rimwn. 



Correlated Protective Devices in Salamanders.f — M. E. Hubbard 

 has found in three species of salamander a relation between the power 

 of autotomy and the presence of poison glands. They form a graduated 

 series. Batrachoseps atienuatus yields comparatively little poisonous 

 secretion when stimulated, Plethodon oregonensis yields it abundantly on 

 the tail, and Diemyctylus torosus pours it out over the dorsal surface of 

 the body. Batrachoseps is eaten with avidity by snakes, Plethodon is not 

 rejected, and Diemyctylus does not appear to be taken at all as food. On 

 the other hand, Batrachoseps practises autotomy on little provocation and 

 at almost any point, Plethodon only as a last resort and at one region 

 only, Diemyctylus not at all. 



Skulls of Teleosts in Relation to Mode of Life.} — F. Supino 

 points out that some cranial characters of Teleosts, notably the amount 

 of cartilage or bone in certain regions, may be correlated with the mode 

 of life. 



Gills and Teeth of Comephorus.§ — A. Korotneff notes some pecu- 

 liarities in the gills and teeth of this fish from Lake Baikal. The gill 

 arches are four in number : they possess on their inner edge specialised 

 papilke, which bear long shield-shaped teeth ; on their outer edge, lancet- 

 shaped gill plates, which are covered on both sides with gill lamella?. 

 In the axis of the gill plate there runs a rod of cartilage, accompanied 

 by an artery and vein. At the point of origin of the gill lamella from 

 the plate, and on its inner side, there arises from the vein a sinus venosus. 

 On the border of this sinus there runs a delicate artery, supplying the 

 artery of the gill leaf. On the flat side of the gill lamella a capillary 

 net communicates on one side with the vein lacuna and on the other 

 probably with the above-mentioned artery. The teeth develop from a 

 mesoderm papilla which projects into the epithelium. Around it the 

 inner layer of the many-layered epithelium forms a cap of prismatic 

 cells, while between the epithelium and the papilla, cement, to which a 

 mesodermic origin is to be ascribed, is laid down. An upward growth 

 of the whole takes place, while the papilla enlarges, the cement in- 

 creases, and the cap cells become long and thread-like. It is doubtful 

 if enamel is present. In origin the teeth are suggestive more of Ganoids 

 than of bony fishes. 



Structure of the Swim-Bladder. || — 1). Deineka makes an addition 



* Zool. Anzeig., xxviii. (1904) pp. 404-5 (1 fig.). 



t Univ. California Publications, i. ( 1903) pp. 157-70 (1 pi.). 



j Atti. R. Accad. Lincei (Rend.) xiii. (1904) pp. 625-31. 



§ Biol. CentralbL. xxiv. (1904) pp. 641-4. 



|| Zeitschr. wiss. Zool., lxxviii. (1904) pp. 149-64 (2 pis.). 



