444 R. I. Pocock — On Eophrynus and Allied Arachnida. 



with that on the following terga, but the remaining large 

 tubercles characteristic of the laminae and of the central portion 

 of these segments are almost undeveloped on the second. A median 

 pair a little larger than the rest that stud its surface, and one on 

 the left-hand side, are all that remain to represent the principal 

 tubercles. The posterior border of the plate, moreover, though 

 marked by a series of granules, is less well defined and more sinuous 

 than that of the other terga. An examination of the plate, in fact, 

 forcibly suggests that it is in process of fusion with that of the 

 third somite. Indeed, were it not for the distinctness of the lateral 

 lamina on the left-hand side, it might be interpreted as the anterior 

 portion of the latter somite. This interpretation, however, leaves 

 unexplained the distinctness of the lamina in question, and of the 

 transverse groove that is continuous with its posterior angle, and 

 traverses the dorsal surface from side to side in a direction parallel 

 with that of the recognized tergal sclerites ; also it carries with 

 it the conclusion that the second tergum is of exceptional size, 

 namely, three times as long as the first and twice as long as 

 the third. 



On the whole it appears to me that the view here adopted, that 

 nine tergal plates are present on the upper side of the opisthosoma, 

 and that the second is reduced in size and modified by the sup- 

 pression of its large tubercles, possibly also by partial fusion with 

 the third, is more in keeping with the facts exhibited than the 

 alternative hypothesis that has been already discussed. 



This view of the existence of nine visible terga on the dorsal side 

 is opposed to that of Haase, Stur, and Ammon, who recognize only 

 eight such plates in certain allied Carboniferous Arachnids they have 

 examined. In the case of Eophrynus salmi, Stur declares the dorsal 

 side to be divided by seven sulci into eight plates. His drawing, 

 however, of the anterior portion of the opisthosoma in his species is 

 by no means conclusive on this point. In the first place, there is 

 a want of definition about this area, due, perhaps, to the bad state 

 of preservation of the fossil ; in the second place, there is obviously 

 space enough between what are described as the first and second 

 terga for the presence of another plate ; in the third place, on the 

 left-hand side nine large segmentally arranged tubercles are repre- 

 sented, whereas, if only eight terga are present, only eight tubercles 

 should be shown. 



So, too, with AniJiracomartus palatinus of Ammon. ^ Eight tergal 

 plates are described. The first is represented as a short plate, as 

 wide as the carapace, laterally attenuated, without lamina, and 

 fitting into the emarginate anterior border of the second. The latter 

 is large, and its lamina extend forwards on each side of the first, 

 almost reaching the posterior angles of the carapace ; but it is most 

 clearly marked with a transverse and procurved sulcus, defining an 

 area of about the same width and nearly the same size and shape 

 as the first tergal plate. This, I suspect, represents the genuine 



. 1 Geogn. Jahresf., 1900, pp. 1-4, figs. 1-3. 



