mVERTEBRATA, CRYPTOGAMIA, MICROSCOPY, ETC. 257 



The enteron runs straight from the mouth to the anus, and is 

 not provided with any appendages or cajca ; the cesophagus, which 

 traverses the ganglionic mass, is narrow; the succeeding portion is 

 widened out, while the rectal region is diminished in size ; the walls 

 are bright yellow, owing to the colour of the epithelial cells ; the 

 contents are of course fluid, and their reddish coloration is probably 

 due to the blood they have sucked ; the enteric tract exhibits move- 

 ments which, almost rhythmical in order, have the character of waves 

 of contraction, and pass from before backwards, and then from behind 

 forwards. The anus has the form of a cleft set along the longitudinal 

 axis of the body. 



With regard to the vascular system, which can only be properly 

 studied in the living animal, little is yet known, though Professor 

 van Beneden has made a number of observations on the subject.* 

 It differs from any arrangement yet described as obtaining among 

 tlio Copepoda, inasmuch as there is a widely distributed system 

 of closed vessels, which have no direct connection with the spaces 

 of the coelom. There is no heart, but below the enteron there arc 

 two longitudinal vascular trunks, and above it a single one, which 

 runs between the paired generative glands : the bright red fluid in 

 these vessels is driven forwards, in the ventral trunks, by the move- 

 ments of the intestine, every contraction of which propels a fresh 

 wave of blood ; while it takes a backward course in the dorsal vessel 

 after having supplied the various appendages. The contained fluid 

 is not provided with any kind of corpuscle, but only fine granules, 

 and here and there a small spherule ; many of the smaller vessels 

 end blindly, and the blood must therefore return by the same course 

 as that by which it went to the peripheral portions of the body. The 

 blood supply is especially rich in the lobato processes of the body, 

 which arc formed by the metamorphoses of some of the hinder 

 appendages, which appear therefore to have taken on the function of 

 respiratory organs. 



The (jenerative organs are always paired, and consist of two 

 glands lying above the anterior portion of the enteric tract; their 

 ducts antl the orifices of the ducts arc likewise paired ; the ovaries 

 are closely approximated to one anotlier, and consist of a much-coiled 

 tifoe on either side, which passes at its anterior extremity into the 

 oviduct ; this is very wide, and is as a rule found to be filled with 

 largo ova; it is a good deal coiled, and towards its hinder end gives 

 (jff a large crccal branch ; at the end of the duct, the duct of the 

 cemcnt-glaud, the seminal vesicle, and the connection with the 

 spermatophore open into it. Not rarely a viscid secretion is found 

 ill the ccmcnt-gland. The seminal vesicle (receptaculum seniinis) is 

 unpaired, and extends some way forwards, but its neck divides into 

 two i)assagcs, one for either oviduct. This last is narrowed near its 

 orifice, whicli is placed on a small brown projection at the side of the 

 abdomen. The organs of the male were carefully described by 

 Professor Claus in 1858; the testes, like the ovaries, lie in tho 

 anterior portions of the thorax, are elongated and pyriform, and so 



* Cf. Ufxl nolo. 



VOL. III. 8 



