36 SUMMARY OF CUKRENT RESEARCHES RELATING TO 



Locomotion of Ribbon-fishes.* — G. Scblesinger discusses forms like 

 Lophotes, Trichivrns, Cepola, Regalecus, Nemichthys, with special refer- 

 ence to their mode of locomotion. He shows that the ribbon-like type 

 is suited for active movement in quiet strata in the water. The loco- 

 motion is due to lateral undulations of the whole body, the number 

 increasing with the rapidity of locomotion. In some forms there are 

 similar specializations in the general bony skeleton, which facilitate for- 

 ward movement. Lateral flexure is made easy, but dorso-ventral flexure 

 is made impossible. It is interesting to find unrelated forms giving the 

 same organic response to similar conditions. 



Anal Fins of Goldfish.f — 0. Storch has studied the paired anal fins 

 that occur in the " Rinkin " variety of goldfish with a long wavy caudal 

 fin. He describes its musculature and skeletal elements, and regards the 

 paired state as affording a clue to the primitive condition of the pelvic 

 fins. The Balfour-Thacher-Mivart theory starts from a paired lateral 

 fin, which is supposed to become differentiated into pectorals and pelvics. 

 The author would start from an unpaired fin, which he supposes to have 

 become split, just as the goldfish's anal fin may be split. The girdles 

 might arise contemporaneously as a correlated variation, evoked by the 

 dynamical conditions at the anterior end of the fin. 



Nervous System of Dogfish. | — 0. Pohmanti gives an account of 

 his elaborate physiological study of the central nervous system of 

 ScyUium catulus and S. canicvia, with particular reference to movement. 

 Numerous experiments were made in order to determine the role of the 

 various parts. 



Dimorphism of Japanese Lamprey. § — S. Hatta calls attention to the 

 fact that in the larger of the Japanese species of Lamprey, namely Za;«/;e^m 

 Japonica, there is great uniformity among the individuals and very slight 

 difference between the sexes, whereas in the smaller species, L. mitsuTcurii, 

 there is great variability and well-marked sexual dimorphism. Further- 

 more it seems that there are two distinct varieties of L. mitsulcurii, 

 differing in size and coloration, which the author proposes to call major 

 and minor. 



Accommodation in various Types. || — C. Hess has studied the 

 accommodation in frog, toad, newt, and salamander. The resting eye 

 is adjusted for distant vision, and is actively accommodated for near 

 vision. It is just the opposite in Teleostean fishes. In Amphibians, as 

 in fishes, the accommodation is wholly due to a change in the position 

 of the lens, which comes about independently of tlie eye-pressure. In 

 the Amniota the accommodation/is due to a change in the shape of the 

 lens. In reptiles and birds this comes about by pressure of the iris and 

 ciliary ring on the peripheral parts of the anterior surface of the lens, 

 and it is independent of the eye-pressure. In Mammals, the roots of the 

 iris and the ciliary processes are not as a rule in direct contact with the 



* Zool. Jahrb., xxxi. (1911) pp. 469-90 (1 pi. and 6 figs.). 



t Arbeit. Zool. Inst. Univ. Wien, xix. (1911) pp. 195-218 (1 pi.). 



X Zool. Jahrb., xxx. (1911) pp. 473-716 (6 pis. and 18 figs.). 



§ Annot. Zool. Japon, vii. (1911) pp. 263-70 (1 pi.). 



II Zool. Jahrb., xxx. (1911) pp. 339-58 (1 pi.). 



