8 



Turner, however, that we owe a more intimate acquaintance with the lætal membranes in Cetacea, his important work forming 

 the foundation for future investigation in this field. 



A detailed description of both embryo and foetal membrane is given by John Anderson in his monograph on 

 the tropical genera of Dolphin, Orcella and Platanista. Further investigation of the placentation is made by Beauregard 

 and Boulart, and Chabry and Boulart, who mention an embryo of Delphinus [delphis, 85 centim. in length, its position 

 and the fn'tal membranes. Klaatsch describes the fretal membranes of the Phocæna communis very exactly, and a very 

 clear description of the placentation in Cetacea as compared witli that in other Mammals, is found in Max Weber's interesting 

 work, "Studien iiber Saugetbiere"', in which the relations of the Cetacea to other Mammals are treated very thoroughly. 



W'lien we add G. Guldberg's study on gravidity in tin-whales, and P. J. van Beneden's valuable "Histoire 

 Naturelle" of Balæna, Megaptera, Ziphoides an'd Delphinidæ, — in which a few remarks on the fætus and placentation 

 occur, — and Kiikenthal's large and important works on the anatomy and developement of Cetacea, the most important 

 contributions to Cetology in the last decade have been named. 



As a conse<|uence of the ruling tendency in biology in the direction of tlio theory of evolution, the question 

 of the phylogeny of Whales has of course been discussed. It was especially Sir H. Flower, — whose investigations in 

 Cetology have earned such merit, — who, about 10 years ago, made this a burning question, earlier naturalists, such as 

 Huxley. Macalister, Marsh and others having only touched upon it; while the famous P. J. van Beneden, in numerous 

 treatises has left valuable material for future comparison. Most of them place the Cetacea in connection with Pinnipedia, 

 a theory wliich is specially expressed by Ch. Julin, while Max Weber does not take his view, but treats exhaustively of 

 the probabilities and affinities between the Cetacea and other Mammals. John A. Ryder takes up a peculiar position in 

 holding that the Hukes of the tail-fin are homologous to liind extremities (.52, p. 482). "The structure of the pinnipeds 

 indicates that the process by which their iiind limbs were directed backwards and partially included together witli the tail 

 in a common integumentary investment, would, if exaggerated, lead to the translocation and fusion of the feet with the end 

 of the sides of the tail, as in the Cetaceans, in which the now degenerate, baclcwardly-displaceJ feet are represented by the Hukes.'' 

 Ryder has been strongly opposed by Kiikenthal. Tiie skeleton of the Cetacean's fore-limb is of course of great phylogenetic 

 interest, and has therefore been deeply studied and utilised in that direction, chiefly by Max Weber and J. Ryder, Leboucq, 

 wlio has made considerable contributions, and P. Allirecht, and J.F.Brandt, who takes up a peculiar position. But above 

 all Kiikcnitlial lias studied '"die Cetaceenhand'', and has thereby gained lasting merit, having had very considerable 

 cuibryological material at his disposal. In addition to Weber, Kiikenthal has also given special attention to the question 

 ol' the Cetacean's positi(ni in ichition to other Mammals, and whether, according to Flower they must be considered as derived 

 from more jiriuiitive IMaiiiniais which liave fitted themselves for an aquatic life like the Sirenia and Pinnipedia, without 

 standing in any phyh)genetic connection with these animals. In Kiikenthal's important work of 1889 be treats of the skin 

 of Cetacea. their hand-skeleton, and, in conjunction with 1 h. Ziehn, their central nervous system. In his work pubHshed in 

 1893. whicli contains a mass of facts, Kiikenthal treats of the developement of the external form of the body, and the 

 structure and developement of the external organs ithe integument, tail-fin, dorsal-fin, pectorals and the formation of the 

 lip, with their functions, the nose, the external ear and mannnary organs), and lastly the developement of the teeth in the 

 Toothed Whale, and their absorption in the Whalebone ^^'hale. 



Of late years, new light has been thrown upon the palæontological position of the Cetacea by an important work 

 on "Zeuglodon", by professor W . Dames, who estabhshes 3 sub-orders of Odontoceti, viz. (1) Archæoceti, (Zeuglodon), 

 i2) Mesoceti (Squalodon). and (3) Euodontoceti (the recent Odontoceti). 



Tliough it might be very interesting to make more copious extracts from different works with regard to the 

 phylogeny of Cetacea. and reflections upon them, I shall not, for the present, enter more iully into the subject. In the 

 following investigation, I shall touch upon certain sidea of this question. What I wish to give in this treatise is an 

 account of the ontdgeiiy of some Odoiitocete species as far as material will permit, and hope by this contribution to fill up a 

 small part of the lacuna which the ontogenic developement of the Cetacea permits us to open up. Certain fresh facts throwing 

 ligiit upon the f a; tal membranes and the gravidity of Odontoceti will also be added. 



