Descrijition of Genera and Species. 65 



hooking spermatophores upon the females. The external branch appears to be in the 

 form of an ordinary swimming plate. The pleopods of the second segment, although 

 not quite so massive as those of the first, are very large and long, and appear to be 

 even more complex. Each has a basal joint to which is articulated a second joint, 

 which in turn supports two moderately long branches of two or three joints each, the 

 details of which have not been ascertained (fig. 4). They appear to be more limb-like 

 and primitive than the terminations of the first pair, and still more so than the corres- 

 ponding parts of the recent Euphausiids, but unfortunately their state of preservation is 

 not such as to allow of their structure being made out with certainty. (There appeal 

 to be other differences between the males and females than that of the pleopods, for the 

 females seem to be as a general rule shorter and more stoutly built than the males). The 

 pleopods of the third segment have much less massive basal joints, and appear to 

 terminate in the ordinary applanated jointed swimmerets (fig. 1). Those of the fourth 

 and fifth tail segments have not been observed, but they were presumably of the type 

 of the pleopods of the third. Small round-shaped bodies have been observed on the 

 sternites of the first four tail segments between the insertion of the bases of the pleopods 

 in exactly the same position in which the luminous organs occur in the modern Xicti- 

 phanes of our own sea lochs (figs. I, 2). One of these organs is shown magnified 

 in fig. 1*. The uropods are well developed and almost carideau in construction. They 

 consist of the ordinary basal joint attached to the sixth tail segment to allow the 

 uropods to act with the telson and its appendages as a tail f:in. The external branch 

 of the uropod has the usual thickened outer margin terminating in a spine. The inner 

 part is, as usual, more web-like, and there is the familiar transverse suture with the 

 terminal lobe frinifed with setie. The internal branch is the ordinary linyuate form with 

 the median strengthening keel, and is a little longer than the telson, while the external 

 branch is slightly longer still. Fig. 9 shows an enlarged restoration of this tail fan, and 

 fig. IC), also enlarged, is that of the recent Enphausia pellucida Dana, lor comparison. 



In many of the specimens the course of the gut, distended with food, is distinctly 

 traceable through the whole of the tail segments, as seen magnified in figs. 1, (i, and in 

 fig. 8, also magnified, the position of the anal opening is shown in a sulcus situated in 

 the hollow joint behind the tumid base. It also shows the terminal lobe of the telson 

 and the articulations for its accessory swimmerets. 



Remarks. — The distention ol' the gut with food found in many of the specimens 

 from this locality appears to point to some external catastrophe or to epidemic disease 

 being the cause of death — -probably the former, as the remains of shoals of nearly 

 complete individuals are found in certain layers. The shales in which they lie 



