600 DR. F. K. BEDDARD OX 



whei-e the same author * remarks upon the rarity of observations 

 upon the uterus of this genus. I find in tlie species with which 

 I am here concerned very definite beginnings of a uterus, in 

 which, however, I have not seen a large and continuous cavity. 

 This consists in horizontal sections through proglottids, which 

 are not fully mature but in which nevertheless the receptacula 

 seminis are full of sperm, of a wide stretch of condensed medul- 

 lary tissue. This structure appears to me to be exactly like 

 the commencing uterus of some other Oestodesf. It lies in 

 front of the ovary and shell-gland, but behind the receptaculum 

 seminis and vas deferens, occupying thus about the width of 

 the segment. It extends to a considerable distance right and 

 left. The string of tissue representing the uterus is mainly to 

 be differentiated from the surrounding medulla by its crowded 

 nuclei. It is not solid but contains numerous cavities of various 

 sizes. Some of these were filled with cells which may well be 

 egg-cells. These cavities are at least frequently of the same size 

 and shape as the oval intei'stices of the medullary mesh work. 

 Later the proglottids (see text-fig. 6) are full of embryos each 

 in its own separate cavity. 



The following assemblage of characters are perhaps sufiicient 

 to define this species, to which I shall be unable to give a name 

 with absolute certainty that it requires a new one. It will be 

 better therefore to leave this matter unsettled for the pi-esent. 



Definition of Davainea sp. parasitic in Struthio masaicus. 



Length 10-14 inches ; greatest diameter of jyroglottids 5 mm. 

 Scolex 1*2 mm. diameter, toith double row of 130 hooks in all: 

 suckers unarmed. Scolex and anterior part of the body abound 

 vnth calcareous corpitscles, ivhich also occur posteriorly. No neck 

 present. Segments of body not longer than broad ; ripe segments 

 not moniliform. Genital pores unilateral. Cirrus-sac reaching 

 to nerve-cord. Dorsal loater-vessel absent from posterior region of 

 body. Ova imbedded singly in parenchytna extending into cortex. 



The above will be sufficient pending a revision of the genus to 

 place the species approximately. 



Gen'Eral Remarks. 



It is pretty clear from the foregoing observations upon the 

 external characters and internal structure of this Cestode from 

 Struthio masaicus, that it is certainly not to be confounded with 

 the species named by v. Linsbow Davainea struthionis, and which 



* " Vogelcestocleii der Aru-Iiiselu." Abli. Senck. Nat. Ges. xxxiv. 1911, p. 254, 

 & tig. 4, p. 252. 



t Cf. e. g. Beddard in the instance of Chajjiiiaiiia tmiricollis, P. Z. vS. 1915 

 p. 434, text-fig. 3. 



