1905. | NEW ENCHYTREID WORM. 563 
The dorsal blood-vessel is anteclitellian in origin and does notseem 
to be connected at its point of origin with any dorsal diverticulum 
of the gut such as exists in Buchholtzia. It arises in the xith 
segment. I could see no “heart body.” 
The exact origin of the dorsal vessel is rather difficult to locate 
exactly in this very minute Enchytreid. I fix the xith segment 
as the point of emergence from the intestinal plexus, since the 
vessel is very much broader here than in the dorsal region of the 
blood-plexus posteriorly * and stands out more from the walls of 
the gut. The vessel is, in fact, in this segment quite twice the 
width that it is anteriorly to the pont in question. Commonly, 
for example in Henlea nasuta, the dorsal vessel is much wider at 
its emergence from the intestinal plexus than it is anteriorly. 
This is confirmed by an examination of a series of transverse 
sections, from which it was evident that the dorsal vessel stood 
away from the walls of the intestine in the anterior part of the 
clitellum ; it was indistinguishable posteriorly. 
Concerning the reproductive organs, it may be observed, in the 
first instance, that the position of the various ducts and pouches 
is perfectly normal. The external orifices of the atria are very 
conspicuous upon the ventral surface of the twelfth segment, in 
line or nearly so with the ventral setze of that segment. These 
sete are, however, absent, and there are no penial sete of any 
kind. The testes and the ovaries occupy their usual segments, 
. é. Xi. and xii. Concerning the exact form of the sperm-duct 
funnel I am unable to give details; but I have identified them 
and satisfied myself that they are of the usual Enchytreid 
pattern. 
The spermathece offer characters of obvious systematic use. 
They open on the one hand into the cesophagus in the fifth 
segment, and on the other by a muscular duct on to the line dividing 
segments iv. and v. I could not find any diverticula. There are 
but a single pair of spermathece. 
In the above description I have only been able to dwell upon 
a certain number of facts which are of systematic importance in 
the group. Of importance in determining the genus are: (1) the 
presence of four bundles of curved sete on all the segments of 
the body, save the first and the twelfth; (2) intraclitellian origin 
of dorsal vessel; (3) absence of any diverticula to cesophagus ; 
(4) simplicity of spermathece and their communication with 
cesophagus. 
Of the thirteen genera allowed by Michaelsen 7, 9, viz., Acheta, 
Michaelsena, Mesenchytreus, Chirodrilus, buchholtzia, Hnchytreus, 
Stercutus, Marionina, and Lumbricillus, are excluded by these 
characters. Though I did not find any dorsal pores, it is clear 
* It must be borne in mind that Pierantoni (“Studi anatomici su Michaelsena 
macrocheta Pierant.,’ Mitth. Zool. St. Neapel, xvi. 1903, p. 409) traces a distinct 
dorsal vessel in the intestinal plexus posteriorly to the region where the former is 
said to commence. But this does not affect the point of emergence. 
+ Oligocheta, in ‘ Das Thierreich’ (Berlin, 1900). 
