of the Surinam Toad. 27o 



but instead thereof were seen the large alveoli containing 

 the embryos. The interior of these cavities was clothed with 

 a delicate pavement-epitlielium, the connective tissue layer, 

 distinguishable as a separate skin, was pigmented, and in it, 

 moreover, ran bundles of smooth muscles, which otherwise 

 are entirely wanting in the coriuni." 



Among the authors of zoological text-books there is 

 probably not one who has gone so far as to acquire informa- 

 tion with reference to the integument of Pipa by means of 

 personal investigation ; at any rate, these manuals invariably 

 state, in almost precisely the same way, that the skin swells up 

 and forms cells, or that by hypertrophy of the skin special 

 cavities are formed for the ova. The statements made by 

 myself upon the subject have been disiegarded. 



Pagenstecher * was the first author who did not pass over 

 my assertions, though he did not altogether agree with them, 

 for he adds : — " Even should it not be the glands themselves 

 that develop into the alveoli, nevertheless by elevation of the 

 skin between the adhering ova a condition similar to glandular 

 invaginations would be produced. That this is actually what 

 takes place is shown by the presence of the pavement- 

 epithelium." 



The text-books on comparative anatomy, too, do not touch 

 upon the question ; Wiedersheim t alone forms an exception, 

 since he writes : — " The alveoli also upon the back of Pipa 

 dorsigera are to be regarded as enlarged cutaneous glands." 

 It is true that the author suppresses the fact that he has 

 borrowed this sentence from me, in consequence of which 

 others were led to believe that he was speaking from his own 

 experience, an assumption that incidentally may here be 

 corrected. 



Recently, however, an opponent of my view, and a decided 

 one, has appeared in the person of Klinckowstrom J, who 

 during a sojourn in Surinam collected a number of these 

 toads from forest-pools in that region, preserved tbem by 

 various methods, and afterwards subjected them to investiga- 

 tion in the Zootomical Institute of the University of Stock- 

 holm. As a result of his studies this investigator states that 

 the alveoli are " simple invaginations " of the skin. 



Now, although I am, it is true, not in a position to appeal 



* H. A. Pagenstecher, ' Allgemeine Zoologie oder Grundgesetze des 

 thierischen Baues uiid Lebens' (Berlin, 1881), 4. Tlieil, p. 732. 



t R. Wiedersheim, ' Lehrbuch der vergleichenden Anatomie der Wir- 

 lelthiere,' 2. Auflage (Jena, 1886). 



X A. von Klinckowstrom, " Zur Anatomie der Pipa americana : In- 

 tegument," Zool. Jahrbiicher, Abth. f. Anat. u. Ontogenie der Thiere, 

 7. Bd. 



Ann. & Mag. N. Hist. Ser. 6. Vol. xviii. 19 



