SPECIMENS OF TRIARTHRUS. 
155 
observed hundreds of specimens through all stages of the laborious process of cleaning the 
matrix from them, undoubtedly was much better equipped to interpret them than any other 
person. 
The drawing is made on the assumption that the appendages are displaced and all 
moved uniformly outward so that the distal ends of the coxopodites emerge from under the 
pleural lobe, whereas these ends would normally be under the dorsal furrow, and the distal 
end of the ischiopodite should reach the margin of the pleural lobe. While it seems very 
remarkable that it should happen, that all the appendages should be so moved that they 
would lie symmetrically a few millimeters from their normal position, nevertheless it is 
found on measuring that they bear the same proportion to the length and width that the 
Fig. 42. — Triarthrus becki Green. Ap- 
pendages of specimen _ 204. Inked in by 
Miss Wood from the original tracing. 
Xio. 
appendages of other specimens do, thus indicating that Professor Beecher's interpretation of 
them was correct. I am unable, however, to see the coxopodites which he has drawn as 
articulating with the two branches of the limb. 
This individual shows, better than any other, the connection of the exopodite with the 
endopodite. Even though the coxopodites are-gone, the two branches of each appendage re- 
main together, showing that the basipodite as well as the coxopodite is involved in the artic- 
ulation with the exopodite. Just what the connection is can not be observed, but there 
seems to be a firm union between the upper surface of the basipodite and the lower side of 
the proximal end of the exopodite, as indicated diagrammatically in text figure 33. 
Measurements: The specimen is 20 mm. long and 9 mm. wide at the back of the cepha- 
lon. From the tubercle on the middle of the first segment of the thorax to the tip of the 
corresponding appendage the distance is 8 mm. The entire length of the exopodite of the 
first thoracic segment is 4.6 mm. The exopodite of the appendage belonging to the seventh 
segment is only 3.5 mm. long. The pleural lobe is 2.5 mm. wide at the front of the thorax. 
Specimen No. 205 (pi. 2, fig. 4). 
Illustrated: Amer. Jour. Sci., vol. 13, 1902, pi. 5, figs. 2, 3 (photographs). 
This is a small imperfect specimen, developed from the ventral side. It retains the best 
preserved metastoma in the collection, but was used by Professor Beecher especially to illus- 
