2o6 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



prostates, curved and smooth. Genital zone large, square, not deeply sunk. 

 No papillae or ridges. Gizzards three, in V, VI and VII. No calciferous 

 diverticles. Small subpharyngeal gland. Very small septal glands in VII-IX. 

 Large racemose sperm-sacs in XI and XII, both postseptal, projecting from 

 the septa. Spermathecae in VIII and IX opening into the intersegmental 

 grooves VII/VIII and VIII/IX, but considerably posterior to the septa. 

 Testes and sperm-funnels in X and XI. Ovaries in XIII. No ovisacs. Sperm- 

 ducts run entirely hidden in the body- wall, fusing at the pore, in XVIII. 

 Prostates in XVII and XIX. One pair of meganephridia in each somite. 

 Nephropores in line with setae b. Last heart in XII. Sacculated intestine 

 commences in XIII. Color pale flesh without any prominent pigment. 

 Septal formula : — 



iv/v, v/vT, vi/vii, VIII/IX, Tx/x, x/xT, xi/xii, xii/xiii. 



Habitat. — Ameca-meca, Mexico. One adult specimen 

 collected by Professor Albert Koebele, in August, 1897, at 

 an altitude of 8,000 feet. 



Affinity. — As far as can be judged from Professor Ben- 

 ham's description of his immature specimen of Trigaster 

 Lankesteri (Benham, 3), Z. ameca-meccB besides having 

 meganephridia instead of plectonephridia, differs in the 

 location of the three gizzards and of the spermathecal 

 pores. In Trigaster JLankesteri these pores are figured by 

 Benham as being in the posterior part of the somite, thus 

 making them preseptal, while in Za^oiecia ameca-mecce they 

 are postseptal. 



Detailed Description. 



SetcB. — The setse are paired, but not very closely. By 

 measurement with a micromillimeter ocular the intervals 

 were found to be as follows: — 

 ^-c=35; c'-3=92; 3-«=35; «-a=ii5; «-3 = 30; ^-^=90; 



The distance between setee ah and cd is almost the same. 



The genial seice, of which there are two in each sac, are 

 much narrower than the ordinary setce. A good view of 

 the tips was not obtained, but they appear to be smooth and 

 slightly curved. 



Somites. — The segments of the body increase in length 

 gradually towards the front end. The clitellar somites 

 are very narrow. The specimen being in a poor state of 



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