304 R. I. POCOCE. 



branch. In Lipliistius also there are two branches, the 

 inner slender and unsegmented, the outer stout and composed 

 of two principal segments. Although in general form the 

 inner lobes {end., PI. 19) of Palaeophonus resemble those 

 of Limulus, they differ from the latter, and approach those 

 of Lipliistius in being unsegmented. Tlie outer branch is 

 broad and flattened, and is somewhat like that of Limulus, 

 except that it is relatively smaller, and lies with its axial 

 line directed, not longitudinally, but obliquely outwards and 

 backwards like the comb of a typical scorpion. It shows, 

 however, no signs of segmentation into so-called '^fulcra" 

 and " intermediate lamellse," such as are found in the combs 

 in the majority of species. Structurally, in short, it is inter- 

 mediate between a typical comb and the outer branch of one 

 of the mesosomatic appendages of Limulus. Furthermore, 

 the fine striae which fringe its posterior edge are, in my 

 opinion, too delicate to be the remains of teeth comparable 

 in shape and size to those of recent scorpions. Rather would 

 I suggest that they are portions of the edges of branchial 

 lamellae which were affixed like those of Limulus to the 

 posterior side of the appendage, with their lines of attach- 

 ment lying at right angles to its longitudinal axis. 



These appendages overlie and almost completely conceal 

 the sternite of the third mesosomatic somite. The stern- 

 ites of the fourth, fifth, and sixth somites, however, are 

 fully exposed and well preserved. They are granular, and 

 resemble the corresponding plates in recent scorpions but 

 for the absence of the muscular impressions and, so far as my 

 observations go, of the stigmata. Peach, however, declares 

 most emphatically that " all four sterna exhibit on the right 

 side undoubted slit-like stigmata at the usual places." It is 

 true that the sternites are somewhat wrinkled laterally, and, 

 as shown on PI. 19, exhibit certain shallow impressions, 

 which, especially in the case of the fourth and fifth sternites, 

 might be mistaken for stigmata; but it is hard to believe 

 that slits as conspicuous as the stigmata of recent scorpions 

 should be so indistinctly preserved on sternites in such an 



