•600 SUMMARY OF CURRENT RESEARCHES RELATING TO 



'Geotrla and Mordacia from Australia and Chili. To these two genera, 

 and to Exomegas, which the author has not been able to investigate, all 

 the Petromyzonts of the Southern Hemisphere are referable. He 

 describes four stages in the life-history of Geotrla chilensis Gray, which 

 correspond generally to those of the European lamprey. There is (1) 

 a larval or ammocoete stage, with two oral lobes, eyes hardly visible, and 

 light colour ; (2) a first stage of metamorphosis, with round suctorial 

 mouth, Avithout teeth, without tentacles, with eyes more distinct, and 

 with light colour ; (3) a second stage of metamorphosis, with round 

 mouth, without teeth, with two tentacles, with cirri, with very large 

 distinct eyes, with a reddish-brown dorsal streak and silver-white colour 

 ■on the sides and below ; (4) a juvenile stage (= Macr ophthalmitis 

 chilensis Plate), with round mouth with teeth and two tentacles, with 

 very large distinct eyes, with blackish-blue colour above and silver-white 

 beneath. 



" Larynx " of Ganoids and Dipnoi.* — R. Wiedersheim has investi- 

 gated Protopterus, Polypterus, Lepidosteus, &c, in search of the founda- 

 tions of the laryngeal skeleton and musculature. In Protopterus and 

 Polypterus there is in the region of the glottis a muscular apparatus 

 which widens and narrows the opening. He distinguishes in both a 

 m. laryngeus dorsalis and a m. laryngeus ventralis, innervated by the 

 vagus. In Protopterus, there is a considerable development of supporting 

 cartilage. From his study he finds himself warranted in distinguishing 

 .a larynx dorsalis distinct from the larynx ventralis. Thus, if the syrinx 

 of birds be included, there are in Vertebrates three distinct larynxes. 



Specific Differences in the Kidneys of Lepadogaster.f — F. Guitel 

 has studied five species of this little sucker-fish. In one species, L. 

 wlldenoicll, there are mesonephric canaliculi composed of several distinct 

 sections and provided with glomeruli. In L.goiianil and L. limacidatus 

 there are mesonephric canaliculi (" pelotonnes ") without glomeruli. In 

 two other species, namely, L. candollll and L. microcephalia, there are 

 neither canaliculi nor<=glomeruli. Thus there is notable specific distinction 

 even in the recesses of the kidney. This result is complicated by the 

 fact that there are sexual differences, for the mesonephric " pelotons " 

 are different in the sexes of L.ffouanil&nd of L. bimactdatus. Further- 

 more, in one species at least, L. bimaculatus, there are seasonal differ- 

 ■ences associated with the periodic development of the gonads. 



Study of the Respiratory Exchanges in Water.:}:— J. P. Bounhiol 

 and A. Foix point out some defects in prevalent modes of studying the 

 respiratory exchanges in water. The essential thing, if normal conditions 

 are to be sustained, is some way of restoring the oxygen to the water as 

 it is used up and of removing the carbonic acid as it is produced. The 

 authors describe a method whereby a known quantity of air circulates 

 with automatic restitution of oxygen and removal of carbonic acid. 



Temperature of the Tunny. §— P. Portier notes that the general 

 belief that fishes have exactly the temperature of the medium in which 



* Anat. Anzeig.,xxii. (1903) pp. 522-35 (9 figs.). 



t Arch. Zool. Exper., ser. 4, vol. i. (1903). Notts et Revue, No. 6, pp. xcv.-c. 



t Comptes Rendus, cxxxvi. (1903) pp. 1270-3(1 fig.). 



§ Bull. Soc. Zool. France, xxviii. (1903) pp. 79-S1. 



