ZOOLOGY. 493 



Sirenians. 



Lepsius (G. R.)- Halitherium Schinzi, dio fossile Sireiie des Mainzer Beckens. Eine 



vergleicbend-anatomische Studien. Mit. 10. Taf. Abhandl, des Mittelrhein. 



Geolog. Vereina, v. 1. 



Cetaceans. 



Flower (W. H.). Abstract of Lectures on tbe Anatomy, Pbysiology, and Zoology of 

 the Cetacea. Brit. Med. Journ. (Lect. I, p. 553-554; II, p. 632; III, p. 717; IV, 

 p. 760; V, p. 794-795; VI, p. 840; VII, p. 876: VIII, p. 962-963; IX, p. 38-39.) 



Development of the ear-ossicles. 



As is generally known, the principal auditory ossicles of mammals are 

 represented by external bones in the inferior vertebrates, but it seems 

 to be yet a question what are the exact equivalents in several cases. The 

 English anatomists — notably Huxley and Parker — have latterly main- 

 tained that (1) the malleus is developed from the first branchial arch in 

 connection with Meckel's cartilage, while (2) the stapes and incus are de- 

 rived from the second or hyoidean arch. This view has now been called 

 into question by Prof. W. Salensky. That embryologist instituted re- 

 searches on the development of the ossicles in embryonic lambs and pigs 

 ranging from 1.5 centimeters long upward, and derived the following 

 conclusions : 



A 1. " The proximal segment, at an early period separated from the 

 cartilage of the first visceral arch, becomes the rudimentary incus. (The 

 second visceral, Reichert's cartilage, here plays no part.)" 



A 2. " The distal moiety of the same cartilage gives rise to Meckel's 

 cartilage {s. str.), together with the rudiment of the malleus.^'' 



B 1. " The stapes is formed independently of the other auditory os- 

 sicles." 



B 2. " It begins as an accumulation of cells around the mandibular 

 artery." 



B 3. "From its first appearance the stapes is a perforate and not a 

 solid plate, though wrongly taken for the latter by all embryologists." 

 (J. K. M. S., I, 18-19, from Morph. Jahrb., VI, 415-432, with pi.) 



In fine, Salensky adopts the old view propounded by Reichert, and 

 which was also originally accepted by Huxley. 



New Jurassic Mammals. 



In the report of the Smithsonian Institution for 1880, a list of the 

 Jurassic mammals, found up to 1880, was given and thirteen species 

 were therein enumerated. During 1881, Professor Marsh added to the 

 list four more, two qf them representing distinct genera, viz : Allodon 

 laticeps and Docodon strigatus. Professor Marsh believed that the former 

 should probably be placed in the Plagiaulacidce and that the latter was 

 most nearly allied to Diplocynodon. The other species were named Cten- 

 acodon iianus and Bryolestes gracilis. As usual for Jurassic mammals, 

 only lower jaws of the several species were found. All were obtained 



