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



equivalent oq the ventral side. It probably therefore represents 

 the tergum of the pregenital somite, and is thus comparable to the 

 first tergite of the opisthosoma in the Pseudoscorpiones and Pedipalpi. 

 The second then will be the tergal plate of the genital somite, like 

 that of the two orders just named. 



The smaller size of these two terga as compared with the third, 

 both in Eophryniis prestvicii and Anthracomartus volJcelianus and 

 palatinus, recalls what is met with in the Pedipalpi, where also 

 the anterior border of the second is emarginate for the reception 

 of the first.^ 



The third, fourth, fifth, sixth, and seventh terga are, apart from 

 their increasing recurvature, similar in form and structure, except 

 that the median tubercles of the third are more coalesced and form 

 a slightly larger and higher cluster. The eighth also is like those 

 that precede it, except that the posterior lateral angle is produced 

 into a spiniform process. A similar process is present upon the 

 marginal lamina of the ninth. The central area of this plate, 

 however, which is relatively narrow and compressed, is furnished with 

 only two tubercles, representing the lateral pair of the four observable 

 upon the preceding terga. Moreover, the tergum of the ninth 

 somite is continuous posteriorly with a quadrate plate occupying 

 the interspace between the marginal plates of the somite. Since 

 there is no segmental line between this plate and the tergum, the 

 former may be regarded as an expansion of the latter. In this case 

 the ninth somite differs from the rest in being furnished with 

 a median as well as two lateral expansions. This was the view- 

 adopted by Haase with regard to Kreischeria wiedei and Anthraco- 

 martus volTcelianus, and by Ammon in connection with Anthraco- 

 martus palatinus. Both these authors, however, were in error, 

 in my opinion, in looking upon the somite in question as the last 

 abdominal somite. For in the figures they have published of 

 A. vdlhelianus and A. palatinus the lateral expansions arising from 

 the penultimate, their eighth, tergum are shown to be continuous on 

 the ventral side, with a sternal area behind which at least one 

 complete somite is represented. The same feature is exhibited in 

 the figure of the ventral side of the abdomen of an Arachnid 

 referred by Howard & Thomas to Brachypyge carhonis. It is 

 also very manifest in the cast of Eophrynus prestvicii now under 

 discussion. Moreover, it appears to me to be an open question 

 whether the terminal median lamina that intervenes between the 

 lateral laminae of the ninth is an expansion of the tergum of that 

 somite or of the tenth (the preanal) somite. When the opisthosoma 

 of Eophrynus is viewed from the underside, the posterior median 



^ Smce the pregeuital somite is of inconstant occuiTence wifhin the class Arachnida, 

 persisting in some orders (e.g., the Pedipalpi, Palpigradi, and Pseudoscorpiones) and 

 obliterated in others (e.g., the Scorpiones, Xiphosurse, and Solifugae), I adopt the 

 suggestion of Kay Lankester ("Arachnida" in Encycl. Brit., SuppL, 1902, p. 524) 

 and regard it as a supernumerary somite, counting the genital somite as the first 

 somite of the opisthosoma. The annexed figures [see pt. ii] are numbered in accord- 

 ance with this -^dew of the matter. This fact must be borne in mind in comparing 

 the figui'es and description. 



