MOORE: HIRUDINEA OF SOUTHERN PATAGONIA. 679 



and coiled about its fellow, would if straightened out, have a total length 

 somewhat greater than the entire animal. The external limb of the loop 

 has a slightly larger and more uniform diameter than the internal and its 

 walls have a firmer consistency, which increases as the muscular structure of 

 the ductus ejaculatorius is assumed. The difference however is slight 

 In one specimen the left epididymal loop passes ventrad to the right lateral 

 nerve of XIX and then bends forward dorsad to the nerve cord and 

 reaches to ganglion XVIII. Just before entering the prostate or atrial 

 cornu, the duct becomes constricted for a short distance. The atrium con- 

 sists of a very small common bursa, opening to the exterior and situated 

 entirely beneath the nerve cord, and of two large globoid-fusiform or 

 broadly ovate cornua, which diverge from beneath the nerve cord and 

 project prominently cephalad, laterad and dorsad within the limits of 

 somite XII. Their somewhat narrowed apices are joined by the sperm 

 ducts (Plate XLIX, fig. 10). 



The ovarian sacs (Plate XLIX, fig. 10) have no anterior lobes (or at 

 least none are discernible in several dissections) and the two simple sacs 

 of irregular form lie in close contact in the ventral sinus between the nerve 

 cord and the sperm sacs. In the case where they exhibit the greatest 

 development, the left sac reaches to ganglion XVIII, the right to XVII. 



Alimentary Canal. The proboscis (Plate L, fig. 16) is stout, nearly 

 cylindrical but very slightly tapering; the anterior end is but little contracted 

 and truncate with fine denticulations on the margin. It reaches in the 

 retracted state from VII ai to XII aj and receives at its slightly enlarged 

 base the pair of thick ducts of the pharyngeal glands. These are a loose, 

 diffuse mass of unicellular glands occupying on each side the lateral por- 

 tions of somites XII to XIV and to a less extent of XL There is no 

 median lobe and the bundles of ducts from each side remain independent 

 of each other. A short, thin-walled oesophagus extends through XIII to 

 the stomach beginning in XIV. 



The stomach is thin-walled throughout and resembles that of G. lineata 

 (Verrill) most closely, the caeca being better developed than is usual in 

 G. stagnalis. Six pairs of these caeca occur. The first, in XIV, are 

 very small and may be absent on one side, or otherwise asymmetrically 

 developed. In XV to XVIII are four pairs of slender caeca of simple 

 form, which (when empty) extend nearly half way to the margins of the 

 body. The pair of large, posteriorly directed ones arises in XIX and 



