14 BULLETIN 69^ UNITED STATES NATIONAL MUSEUM. 



is situated the yolk gland (fig. 3, y. g.) ventrally, and the shell gland 

 dorsally. The yolk gland measures from 75 to 100/x in diameter and 

 the shell gland from 30 to 50/^. 



As in other members of the genus Davainea^ a definite functional 

 uterus is not developed. The eggs (fig. 4, emh.) in gravid segments 

 are scattered throughout the medullary portion, isolated in the pa- 

 renchyma and not grouped together in capsules. They are sur- 

 rounded by three membranes, a thin inner one close to the oncosphere, 

 which measures 20 to 25/x in diameter, a thicker middle one 27 to 33/a 

 in diameter, and a thin outer membrane 35 to 50/x in diameter. The 

 last is apparently deposited by small cells 4 to 6/x, in diameter, with 

 deep staining nuclei about 2/* in diameter, which largely fill up the 

 spaces between the eggs. 



Remarlcs. 



Davainea compacta Clerc (1906, p. 725, fig. 22) from Oriolus 

 galhula is very similar to D. rhynchota. As described by Clerc it is 

 150 mm. in length by 1.3 mm. in breadth. The scolex is 330/^, in 

 diameter. The rostellum is armed with about 400 hooks arranged in 

 two rows. The larger hooks measure 15/* in length. The hooks on 

 the suckers measure 10/x in length. The segments are always broader 

 than long. The genital pores are unilateral and the genital canals 

 pass between the excretory vessels. The testicles are about 25 in 

 number and the cirrus jjouch measures 150/x, in length. The ovary 

 occupies about one-third the width of the segment. The eggs are 

 verj^ small, the embryo measuring but 14/a in diameter, and they are 

 contained singly in egg capsules. 



Davainea compacta and D. rhynchota correspond very well in the 

 size of the head, number, and size of hooks on the rostellum, their 

 arrangement in a double crown, size of the hooks on the suckers, 

 unilaterality of the genital pores, shape of the segments, number 

 of testicles, size of the ovary, and the arrangement of the eggs singly 

 in egg capsules. Davainea compacta^ however, is a much longer 

 species than D. rhynchota (not an important difference), the cirrus 

 pouch is somewhat larger, and the eggs are much smaller, the embryo 

 of the former being but 14/* in diameter, of the latter about 25/a. The 

 two apparently differ in regard to the rostellum. The presence of 

 spines over the surface of the very prominent rostellum, and the ro- 

 sette arrangement of the hooks are marked features of Davainea 

 rhynchota^ which would hardly have been overlooked by Clerc if 

 they were present in Davainea compacta. The differences between 

 the two forms seem fully sufficient to justify the recognition of the 

 two species. 



Of the tapeworms which have been reported from woodpeckers, 

 Davainea cruciata (Eudolphi) and D. longispina Fuhrmann, 1908, 



