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CALIFORNIA ACADEMY OF SCIENCES. 
DETAILED DESCRIPTION. 
Body-wall. "The prostomium with bueeal cavity is strongly eversible, forming 
a bladder-like apex to the body, as is so frequent in oligochzeta. Somite i is very 
narrow, especially laterally, and may readily, when viewed from the exterior, be taken 
for part of the prostomium. 
The body-wall contains the usual layers of which the muscular fibers show the 
same bipinnate arrangement as in Lumbricus, ete. This arrangement is less regular 
and pronounced in the anterior somites, but quite plain in the genital and clitellar 
ones, especially so on the ventral side, immediately below the nerve-cord. _ 
Sense organs of the epidermis. All the species of Benhamia described here 
possess a continuous row of sense organs, in the equatorial plane of each somite, be- 
tween the setse. Outside of this equatorial circle I haye not found them anywhere 
in the epidermis; there, however, they are very plain and prominent, appearing under 
low power and in longitudinal sections, as a large pellucid spot in the center of each 
somite. The organ consists of two distinct kinds of cells, a double line of large lunate 
cells, surrounding a row of sense cells, several layers thick. These lunate cells are 
generally three or more thick in the row, evidently modifications of the common 
goblet cells of the epidermis. They do not stain with the ordinary aniline colors, or 
only so with difficulty, and generally remain transparent and white. These lunate 
cells run continuously around the somite, and enclose between them bunches of sense 
cells, which may now and then be seen to penetrate the cuticle (fig. 20). Somewhat 
similar sense organs have been known in Lumbricus, etc., for considerable time, but 
have lately been described more in detail by Richard Hesse and F. E. Langdon. 
The sense organs of Benhamia differ from those of Lumbricus agricola (probably a 
collective name used for some East American Allolobophora) in two prominent 
points. Presence of the large lunate cells in Benhamia, which are not seen in 
Lumbricus. The continuous and broad circle of these organs in Benhamia, while in 
Lumbricus they appear to be much further apart. Unfortunately my Benhamias 
were collected at a time when no special preparation for nerve structure was feasible, 
and this made it impossible to work out the details as minutely as desirable. The 
work had already been finished when Langdon’s beautiful paper reached me. 
Fig. 20 represents a section of the body-wall in somite iv. Letters org. signify 
the sense organ. 
3esides these epidermal sense organs I find in all the Benhamias, observed by 
me, a large zone in the buccal cavity characterized by almost cubical transparent 
cells arranged in one single row deep, just as the epithelial cells in the pharynx, but of 
the same nature as the transparent cells in the sense organs of the epidermis. This zone 
is nearly always folded against itself like a sac, and is of considerable extent, as long 
or longer even than the pharynx. In certain places apparently scattered about, but 
principally near the opening of this sae, I find clusters of sense cells of the same 
structure as those of the epidermis. They are all narrow, do not reach below 
in the ccelomie cavity, but end in this direction in line with the pellucid cells and 
connect at the end with nerve fibres. The free ends penetrate above in what ap- 
