54 BULLETIN: MUSEUM OF COMPAKATIVE ZOOLOGY. 



The crop bears seven pairs of lateral diverticula, as in G. elegans and the 

 closely related European G. complanata, with both of which this species has 

 many points in common. The first pair of diverticula arise in the anterior or 

 middle part of somite xiii. and are two or three lobed, the anterior lobe being 

 prolonged forward through somites xii. and xi. The five following pairs of 

 crop diverticula arise in the middle of somites xiv.-xviii. respectively, and 

 are usually bilobed distally. The last (seventh) pair of crop diverticula ex- 

 tend far back of their origin in somite xix., often into somite xxiii. They 

 give off secondary lateral diverticula, a pair in each of the somites through 

 which they extend. 



The crop diverticula are often a conspicuous feature of this species when 

 viewed in a living condition from the ventral side of the animal, for numerous 

 large green chromatophores aggregate about the crop and show through the 

 clear ventral body wall the form of the crop outlined in green. 



/. Nephropores, Nervous System. 



The nephropores (nph'po., Figure 3i) open ventrally, anterior to the middle 

 of the sensory ring of a somite, as stated by Whitman ('91*). They are present 

 in the eighth and all the following triannulate somites. 



I have nothing new to add to Whitman's ('92) excellent account of the cen- 

 tral nervous system. It is important to notice, however, the arrangement of the 

 ventral capsules in the brain region (Figure 3 6). Those of neuromeres iii.-vi. 

 all lie in a single row in the median plane; that is, have what I have called the 

 tandem arrangement. The ventral capsules of neuromere Ii. (^, S, Figure 3 b) 

 have the side-by-side position found in all the species examined b}' me. 



Figure 3 a is a dorsal view of the brain and shows that the supra-oesophageal 

 commissure in the species lies far forward in what may well be regarded as 

 its primitive position. 



The less crowded condition of the brain capsules in this as compared with 

 other species is interesting, as showing that the smaller the leech is, the more 

 crowded are its brain capsules likely to be (compare page 50). 



g. Papill.e, Coloration. 



I have reserved to the last, in describing this species, the discussion of papil- 

 Ise and coloration, for it is on the basis of these characters alone that I am able 

 to distinguish two varieties, plana and rugosa, which I find associated together, 

 but apparently without intergrading forms, in collections from Cambridge, 

 INIass., Lake Chautauqua, N. Y., Lake Forest, 111., and Wellsville, Kan., a very 

 wide range extending across the Mi-ssissippi valley and the Atlantic seaboard. 



(1) Var. plana Clepsine plana Whitman, '91'). 



This variety has a relatively smooth skin, which bears dorsally small dome- 

 shaped papillae, the most conspicuous of whicli are placed as indicutcd by stars 



