THE BATRACIIIA OF NORTH AMERICA. - 239 



aspect of the tliamb aud more rarely spnr-like tubercle.:, on the breast; 

 the body is sometimes shielded with hardened poiuts on therngosities, or 

 the lip surrounded by an arched series of corneous rugae. In tho Lep- 

 todactylus pentadactylus Laur. a huge acute process of the m;t;icarpal 

 of the thumb, Plate 73 (fig. 32), projects inwards. Its apex is cov- 

 ered by a horny cap, and it is a formidable grappling-hook to aid the 

 male in retaining his hold. There is added to this in the saine species 

 a horny plate on each side of the thorax of the male, from which project 

 three acute poiuts. With these fixed in ber back aud the thumb spikes 

 in her breast th<i females cannot escape. Structures like this do not 

 appear in the Firmisternia. Here the inferior elements of the scapular 

 arch abut against each other, so that the thoracic cavity does not con- 

 tract on pressure, and the possibility of the male retaining a (inn grip 

 on the female is thereby greatly increased. In the Cystlgnathiis pachy- 

 piis the males exhibit a permanent enlargement of the brachium, depend- 

 ent on largely developed anterior and posterior alie of the humerus. 

 {Vide Giinther, Ann. Mag. N. H., ISS'J.) 



The various ways in which the eggs are deposited by the female are 

 expressed in the following table from Boulenger. I add the peculliar 

 habit of the genus Deudrobates, as observed by H. H. Smith in Brazil. 



I. The ovum is small and the larva leaves it in a comparatively early embryonic con- 



dition. 



A. The ova are laid in the water. 



Probably the majority of Batrachiaris ; all European forms except Alijles. 



B. The ova are deposited out of the water. 



a. In holes on the banks of pools, which become filled with water after 

 heavy rain, thus liberating the larvte. 

 Leptodactijlus occllaius L. ; L. myslacinus Burin.; PaJudicola 

 gracilis Blgr.* 

 J). On leaves above the water, the larvfe dropping down when leaving the 



Chiromantis rufescens Gthr. ;t Phi/llomedusa iheringii Blgr. 



II. The yolk-sac is very large, and the young undergoes the whole or part of the 



metamorphosis within the egg ;; at auy rate the larva does 

 not assume an independent existence until after the loss of 

 the external gills. 



A. The ova are deposited in damp situations or on leaves, and the embryo leaves 



the egg in the perfect air-breathing form. 

 Eana opisthodon Blgr. ; t Hi/lodes martinicensis Dum. & Bibr. ^^ 



B. The ova are carried by the parent, 



a. By the male. 



a. Round the legs ; the young leaves the egg in the tadpole state. 

 Alytes.W 



' Heusel, Arch. f. Naturg. 1867, pp. 124, 129, 138. 

 t Buchholz, Mod. Berl. Ac. 1875, p. 204, and 1876, p. 714, PI. ii. 

 t Boulenger, Trans. Zooi. Soc, xii, 1S86, p. 51. 



^^ Bello y Espinosa, Zool. Gart., 1871, p. 351 : Bavay, Ann. Sc. Nat. (5), xvii, 1873, art. 

 16 ; Peters & Gundlach, Mon. Berk Ac. 1876, p. 709. 



II Demours, M^m. Ac. Sc. Paris, 1741, p. 13 ; De I'lsle du Dr6neuf, Ann. Sc. Nat. (6), 



III. 1876, art. 7. 



