110 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxvi. 



the extremity under the abdomen of the female, so that the ventral 

 surfaces of the last segments are toward each other. The copulatory 

 apparatus of the male is then pushed out, while the female ])ends the 

 tube upward so as to leave the sexual opening free. Copulation lasts 

 for about half a minute, when the female begins to move and the male 

 leaves her back, but the connection is not at once broken, and the 

 stronger female drags the attached, struggling male behind her for 

 some distance. One male fertilizes a number of females successively. 

 In one case Jordan states that a male of Phldsothrljys hrunnea Jordan, 

 in one-fourth of an hour, fertilized six females, and his spermaries 

 were still about half tilled. 



In the Terebrantia the males are carried around upon the backs of 

 the females and the union takes place in much the same manner as has 

 just been described for the Tubulif era. 



DEFORMITIES. 



Slight deformities are by no means rare. The most common form 

 consists in a reduction in the number of segments in one or both anten- 

 nge, brought about, in most cases, by the fusion of two or more seg- 

 ments at the end, though intermediate segments are sometimes want- 

 ing. It frequently happens that the antenna with fused segments is 

 scarcely shorter than the normal one. Only very rarel}^ does it appear 

 that a redaction in number is the result of injury, though this would 

 seem very possible. So far as is known, an increase over the normal 

 number by a division of segments never takes place. Sometimes the 

 wings are so deformed as to be useless. Deformities in the abdomen 

 are ver^^ rare, but I have found two cases. One in which the posterior 

 segments were constricted being abruptly smaller than the preceding, 

 the other with a half segment wanting on the left side at about the 

 middle of the abdomen. The right half of the segment was wedge- 

 shaped, reaching in to the median dorsal line and giving the abdomen 

 a corresponding crook at that point. 



REPRODUCTION. 



The method of reproduction in this group is of interest and also has 

 an important bearing upon its distribution. So far as known, it is 

 always oviparous and sexual, but two distinct forms are common in 

 most species. 



Bisexual T&production. — This is the normal and most common form, 

 but the two sexes are not found in anything like equal proportions, as 

 females are almost alwaj's more abundant than males. This nia}^ be 

 the case and reproduction yet be entirely bisexual, as in some species, 

 perhaps in all, one male fertilizes a nmnljer of females. In a few species 

 the males are found abundantly throughout the year; in others the}' are 

 abundant only at certain seasons; in others males are rarely found at 



