6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8o 



selves are segmented near the end. Barrows (1925) states that the 

 tendon- of the flexor of the claws divides, and each element traverses 

 the long proximal part of the claw to attach to the terminal part. The 

 writer has been unable to find a division of this tendon and is of the 

 opinion that it attaches in the usual manner at the claw bases. It 

 was noted, however, that a tracheal branch traverses most of the 

 length of the basal element of each claw. When a solpugid leg is 

 compared with that of a primitive mite, a tick or a primitive phalangid 

 or with certain other arachnids, the homology of the leg segments is 

 indicated. 



While discussing the legs of solpugids it is pertinent to recall 

 that Bernard ( 1896) concluded, " that the ' sterna ' along the abdomi- 

 nal segments represent rudimentary limbs which have simply flattened 

 down." He claimed that the two pairs of stigmatic opercula repeat 

 the genital opercula so closely that they must also be vestigial appen- 

 dages ; that the abdominal vestiges are often covered with hair differ- 

 ing from the hair on the rest of the abdomen; that the same differ- 

 ence applies to color ; that the vestiges meet in the middle line 

 like the coxae of the functional legs ; and finally that the stigmatic 

 apertures, which are always associated with rudimentary legs, have 

 moved into the ventral middle line. 



THE LEG SEGMENTS OF PRIMITIVE PHALANGIDS 



The phalangids with which most American entomologists are 

 acquainted are called daddy-long-legs. They are cjuite different in 

 appearance from the most primitive members of the group which are 

 placed in the suborder Cyphophthalmi. Members of this suborder do 

 not have the long many-ringed legs of the familiar daddy-long-legs. 

 They are much smaller and in appearance are mitelike. The resem- 

 blance to mites is more than superficial. According to the writer 

 (Ewing, 1923) it is from very similar arthropods that the mites have 

 evolved. 



The leg of one of the Cyphophthalmi, as represented by Holosiro 

 acar aides, has been regarded as seven-segmented with the addition of 

 the foot. However, the first two legs have a divided basal segment, 

 the most proximal section being known as the maxillary lobe. In 

 Holosiro acaroidcs (pi. i, fig. 2) there are rudiments of this lobe of 

 the basal segments to all the legs though they are very small for the 

 last two pairs. 



Unfortunately the writer has had only two specimens of this primi- 

 tive group for study and these are balsam-mounted types. It may 



