THE ECTOPARASITES OF THE RED GROUSE 355 



of the intestine, and near the base each swells into an oval vesicle. The 

 tubules are long, as long almost as the body, and are coiled away amongst the 

 viscera. 



The fat-body is very definitely arranged, there being paired pouches of it at the 

 sides of each segment. In the cavity of these pouches are five collections of 

 oval structures, which may be the five pairs of ovarian tubules, showing the ova, 

 but somewhat similar structures occur, in equal numbers, in the male abdomen. 



We have not made a detailed examination of the nervous system, but may 

 remark that it consists of a brain and a large infra-oasophageal ganglion Nervous 

 in the head and of three ganglia in the thoracic segments. The last s y stem - 

 of these is the largest, and it supplies nerves to the organs of the abdomen. 



This, again, we have not examined, but Wedl * and Kramer 2 have seen and 

 described, the hearts of several species. They seem to conform to the circulatory 

 usual insect type, but the number of chambers is small, Wedl says only syst( 

 one in Menopon pallidum, situated in the last abdominal segment but one. 



We have not investigated the reproductive organs in any detail, but it may 

 be mentioned that in the Ischnocera, the subdivision of the Mallophaga to which 

 Goniodes and Nirmus belong, there are four testes, the two on each 

 side being united by a common vas deferens, which leads into a vesicula ductive 

 seminalis, which, though bilobed, is usually unpaired ; from this an 

 ejaculatory duct leads to a retractile penis. Morphologically there is an invagina- 

 tion of the body-wall of the last abdominal segment to form the genital cavity, 

 and the various plates and bars are chitinous thickenings in the walls of the 

 invagination. In the centre of the genital cavity lies the penis, which is 

 strengthened by chitinous rods and bars, and is capable of being protruded 

 and retracted by a complicated system of muscles. In the male the anus has 

 been involved in the invagination and comes to open dorsally into the genital 

 cavity. This is not the case in the female, where the invagination is not close 

 to the posterior end, but is formed by an invagination of the eighth abdominal 

 segment. The vagina opens anteriorly and dorsally into this chamber, and 

 passes into a long coiled oviduct which splits into two collecting-ducts, and these 

 terminate in five ovaries on each side of the body. The ovaries dwindle out 

 anteriorly, and their thread-like forward ends unite into a common termination. 



An excellent comparative account of the reproductive organs of the group is 



1 "Sitzungaberichte der mathematisch-physikalischen Clasae der Kaiserlichen Academic de Wissenschaften 

 xvii. Vienna. 



2 " Zeitschrift fur wissenschaftliche Zoologie," xix. p. 452, 1869. 



