NO. 2267. 



NEW BRANCHIOBDELLID WORMS— ELLIS. 



24^ 



Fig. 7— Upper jaw of type- 

 specimen OF XIRONOGITON OC- 

 CIDENTAMS ELLIS, FROM CRAB 

 REEK WASUINGTON. TYPE IV. 



midway between the levels of the two dorsal diverticula; dental 

 formula 6-6, upper jaw type IV, lower jaw type IV, but with the 

 two teeth of the "a" order unequal in size; tooth plan of upper jaw 

 C-B-a-a-B-C teeth of the "6"' order being slightly smaller than 

 those of the " B " order but larger than those of the " a " order, the 

 two " a " teeth unequal ; differences in size of teeth slight so that the 

 jaws approach the subequal-toothed jaw type; anterior nephridia 

 alternating in segments II and III, opening to the outside through 

 separate pores on the dorso-latoral surface of segment III; sper- 

 matheca simple; testes present in segments V and VI; vasa defer- 

 entia from segments V and VI joining the 

 atrium in segment VI; a long accessory 

 sperm tube present; alimentary canal not 

 conspicuously expanded in the first three seg- 

 ments, wider in segment IV, increasing in 

 diameter in segments V and VI, narrowing 

 in segment VII, in which segment the 

 intestine forms a more or less definite 

 " >S' "-shaped curve ; intestine narrowing rap- 

 idly in the anterior half of segment VIII and continuing as a some- 

 what crooked tube to the anal opening on the dorsal surface of the 

 posterior half of segment IX; because of the reduced condition of 

 segment IX, the anal opening is subterminal; adhesive glandular 

 disks on segment VIII prominent, those on segment IX incon- 

 spicuous. 



The two specimens from which this species was described measured 

 4.5 and 5 mm., respectively. X. occidentaUs resembles a large, much 

 extended specimen of X. hwtahilms (Moore). It is easily separated 

 from that species by the glandular disks on the ventral surface of 



segments VIII and IX and by the distinct 



segmental junctions. 



XIRONOGITON OREGONENSIS. new species. 

 Plate 10, figs. 1, 2; plate 12, flg. 1. 



Type— C^t. No. 17639, U.S.N.M., body 

 length 1.3 mm., Eugene, Oregon (J. E. Guth- 

 berlet), October, 1914, on Astacus klamath- 

 ens'ir, Stimpson (det. Faxon). 

 Paratypes.— Four, Cat. No. 17640, U.S.N.M., and 10 others, col- 

 lected with the type. 



Description. — Body distinctly depressed, general outline of con- 

 tracted specimens racket — or flask-shaped, extended specimens con- 

 spicuously wider in the posterior half of the body than in the an- 

 terior; liead and body segments I and II subequal and subterete; seg- 

 ment IV distinctly wider than segment III and somewhat depressed; 

 segments V to VIII conspicuously wider than the anterior portion of 



Fig. 8.— Lower jaw of type- 

 specimen OF XIRONOGITON OC" 

 CIDENTALIS ELLIS, FROM CRAB 

 CREEK, WASUINGTON. 



