AMPHIBIA. 407 



Gymnophiona, and is probably used as an intromittent organ. Specialised 

 copulatory organs are not present. 



Caecilia compressicauda among Gymnophiona is viviparous, as are 

 Salamandra maculosa and 6*. atra. Other Amphibia are oviparous, and 

 the ova are generally laid in water, either in floating masses (Anura} or 

 affixed to water-plants (Triton, Axolotl among Urodela). Certain exceptional 

 cases may be noted among Anura. The ova are stored in a dorsal sac 

 opening above the cloaca in Notodelphys and Nototrema : in cavities one for 

 each ovum, formed by hypertrophy of the dorsal skin in Pipa, the male 

 spreading them on the backs of the female. They are affixed to leaves of 

 plants in one or two instances, e. g. by Hylodes martinicensis : are carried 

 by the male Alytes obstetricans twisted round the hind-limbs until the Tad- 

 poles are ready to escape, and by the male Rhinoderma Darwinii in the 

 enlarged croaking sacs 1 . Impregnation is external in Anura. The male 

 Urodele, so far as is known, deposits a spermatophore, formed by the 

 cloacal and pelvic glands (?), which is taken up by the female and therefore 

 impregnation is internal, as it must be in Gymnophiona. There is a sexual 

 congress in Anura, and in one Urodele at least (Glossoliga Hagenmulleri). 

 The ova are enveloped in albumen secreted by the oviduct. They are 

 usually small. Segmentation is as a rule complete, but in some instances 

 there is a large amount of yolk and a yolk sac, as in Teleostean fish, e. g. 

 Epicrium ghttinosum, Pipa, Alytes. Segmentation is unequal. The epiblast 

 consists of two strata, an epidermic and a nervous, from the first in Anura, 

 a condition attained at a later period in the Newt. There is a metamor- 

 phosis, the degree of which varies. The larva has usually a fish-like aspect : 

 the head not well marked off from the body : a long tail with azygos fin : 

 three pairs of external gills : no limbs except mere indication of the fore- 

 limbs in the Newt : adhesive organs in the Anura, and a pair of supporting 

 processes below the neck in the Newt. The young Caecilia compressicauda, 

 Salamandra atra, Pipa and Hylodes inartinicensis have the adult form when 

 they come into the world. The two first named have an intra-uterine 

 development, the latter of the two having long gills, which are lost if the 

 young are transferred to water, a new and shorter set being developed. 

 Pipa passes through its metamorphosis in the cavity of the skin in which 

 the ovum lies. Hylodes has an intra-ovular metamorphosis, and in two 

 species of Nototrema the young quit the dorsal pouch in a perfect state. 

 Epicrium glutinosum loses its external gills before it is hatched, and the 

 larva wanders from the spot in the earth where the eggs are laid and leads 

 an aquatic life for a time. It swims by means of its tail, which is provided 

 with a fin. The tail is lost in the adult as in other Gymnophiona. The 

 Anuran Tadpole also loses its tail by absorption. The changes which take 

 place in the metamorphosis are profound in the Anura and higher Urodela^ 



1 See remarks and a table by Boulenger to a paper by von Ihering in A. N. H. (5) xvii. 1886. 



