1042 



SUBMAMMALIAN VERTEBRATES 



At copulation the mixture is ejected into 

 the oviducts of the female (Gilbert, 1943). 



The anal fin of species of Xiphophonis, 

 Molliensia, Gambusia, and Fundidus be- 

 comes specialized after puberty into a gono- 

 podium which is used as an intromittent 

 organ (van Oordt, 1925; Vaupel, 1929; 

 Turner, 1941a, b; Cummings, 1943a). In 

 some poeciliids this fin, although elongated, 

 is not used for intromission, but instead is 

 employed to "fan" the ejected sperm toward 

 eggs which also have just been discharged 

 (Newman, 1907). 



The male's anal fin is employed for in- 

 ternal fertilization by at least one oviparous 

 fish, Apogon imberbis. The fertilized eggs 

 are then deposited in a clump which the 

 male picks up, carrying the mass in his 

 mouth during most of their incubation 

 (Garnaud, 1950). One wonders how hungry 

 the father becomes and how lie resists 

 temptation. 



Amphibians 



The majority of urodeles fertilize their 

 eggs externally in the water, whereas nearly 

 all female salamanders obtain sperm for 

 internal fertilization by picking up sperma- 

 tophores with their cloacal labia. According 

 to Noble (1931), both Ascaphus, a very 

 primitive frog, and the Gymnophiona, an 

 order of limbless, burrowing amphibians, 

 practice internal fertilization with the aid 

 of an intromittent organ which is simply 

 a muscular, highly vascular extension of 

 the cloaca. The rectus abdominis muscles 

 of Ascaphus draw this copulatory tube an- 

 teriorly so that it can be thrust into the 

 cloaca of the female. Since N ectophryno'ides 

 occidentalis is viviparous (see below) it 

 must also practice internal fertilization, but 

 the mechanism is unknown (Angel and La- 

 motte, 1944). 



Reptiles 



In lizards and snakes the paired penial 

 sacs are posterior diverticula of the cloaca 

 and lie caudal to it in pouches under the 

 skin of the tail. Before mating the sacs are 

 drawn by muscle action into the cloaca and 

 then, as they become erect, evert themselves 

 like the fingers of a glove through the 

 cloacal outlet. The semen passes through a 



spiral furrow in each penis. The latter is 

 then withdrawn into its recess by an elon- 

 gated retractor muscle. 



In turtles and crocodilians the single, 

 arched phallus is a solid, cavernous struc- 

 ture. It is attached to the ventral wall of 

 the proctodeum (the terminal chamber of 

 the cloaca), from which it is everted on 

 erection. The semen is carried in a deep 

 groove along the convex penial surface, the 

 groove being converted into a canal during 

 erection." In these reptiles the phallus of 

 the female is morphologically similar to, 

 but much smaller than, that of the male. 



VII. Other Specialized Structures 

 in Males 



Fish 



Evidence will be presented later that the 

 dimorphism in size and color seen in many 

 species is at least partly under the con- 

 trol of the sex hormones. Sometimes the di- 

 morphism is extreme. For example, late in 

 his life the male pink salmon, Oncorhynchus 

 gorbuscha, grows a huge hump on his back, 

 and his head becomes large and bizarre in 

 appearance (Davidson, 1935). The adult 

 male sockeye salmon, 0. nerka, develops 

 the dorsal hump, an elongated jaw, and a 

 thickened skin (Weisel, 1943). The ''sword," 

 a greatly elongated portion of the caudal fin 

 which gives Xiphophonis its name, is an- 

 other conspicuous male secondary sex char- 

 acter (van Oordt, 1925). 



Amphibians 



Many male frogs and toads have wart- 

 like excrescences on their fore limbs in the 

 breeding season. These "nuptial callosities" 

 help the male to cling to the female during 

 amplexus. Bles (1905) described the "nup- 

 tial asperities" (a delightfully ambiguous 

 phrase) of Xenopus laevis, an African toad. 

 Other species have similar structures, often 

 spiny. Braun (1878) reported "large, round, 

 black-colored warts" on the hind limbs of 

 male Triton viridescens and erroneously 

 supposed that these growths also made pos- 

 sible a firm grip on the female during mat- 



"Wiedersheiin, 1886: Gadow, 1887, 1923; Coe 

 and Kunliel, 1905; Moens, 1912; Reese, 1915; 

 Nicholson and Rislev, 1941. 



