324 



developed, and armed with larger and more spinose tubercles than those 

 on the corresponding ridges of the posterior portion, one a little behind the 

 mid-length on each ridge being larger than any of the others, but the central 

 ridge is obsolete. In its place, just in advance of the cervical groove, 

 there is an ovate lanceolate or narrowly spear-shaped area, which is ele- 

 vated at the pointed end anteriorly, shallowly depressed posteriorly, and 

 margined with a single row of small tubercles. Immediately in front of 

 this area is a pointed or spinose tubercle, almost in a line with the largest 

 tubercle on each of the lateral ridges, and still farther forward there are 

 two similar tubercles at a short distance from the anterior margin and 

 about seven millimetres apart. On the posterior portion or scapular 

 arch, the three longitudinal ridges are minutely tuberculated, and extend 

 from the posterior margin to the cervical groove, where they each termi- 

 nate in a pointed tubercle larger than any of the rest, but the central 

 ridge is shorter than either of the two lateral ridges. Anterolateral 

 angles of the carapace, each armed with a nearly straight but slightly 

 divergent spine. Rostrum, central portion of the anterior margin, and 

 position of the eyes unknown. External antennfe broad and flattened at 

 their bases, inner antenna cylindrical at theirs. Walking feet slender, 

 as is usual in the genus. In addition to the spines and tubercles on the 

 lateral ridges and elsewhere, as already described, the whole of the upper 

 surface of the carapace is minutely granulose and apparently setose, num- 

 bers of minute objects which seem to be detached set*, being plainly 

 visible under an ordinary lens. 



"Two miles up the Puntledge River, Vancouver Island, Rev. G. W. 

 Taylor, 1889 : a good specimen of the carapace, with the rostrum and a 

 small piece of the anterior extremity broken off, but with considerable 

 portions of the ambulatory feet and the bases of the inner and outer 

 antennfe preserved. This interesting fossil is now in the Museum of the 

 Geological Survey of Canada. [See PI. 40, Fig. 1.] 



" Hornby Island, W. Harvey, 1893: a less perfectly preserved speci- 

 men, showing most of the carapace (but not the rostrum), portions of the 

 ambulatory feet, and the dorsal aspect of four segments of the abdomen, 

 though it is uncertain whether their margins were denticulated or not." 



In regard to this Hornby Island specimen. Dr. Woodward says that it 

 " shows the cephalothorax and a portion of the base of the left antenna. 

 The three characteristic longitudinal ridges, the small central pear-shaped 

 area in front of the neck-furrow on the carapace, and five of the abdomi- 

 nal segments can also be seen. Their margins are denticulated." (Geol. 

 Mag., Sept., 1900, pp. 393 and 396.) 



Three other specimens of this species have since been obtained, which 

 are thus described by Dr. Woodward (op. cit., p. 393.) 



