522 AN ARACHNID FROM THE COAL 



not indicated in his figure, was "plainly visible through the 

 eighth segment near its anterior border." This accords well 

 with its position in the Crawcrook example ; it is precisely the 

 nearness of the circular plate to the anterior border of the 

 eighth segment that constitutes the chief peculiarity of this 

 region. In Pocock's figure of his species, projecting spiniform 

 angles are shown at the back of the outer border in segments 

 6 and 7, but he states that the existence of these spines is by 

 no means certain, and none were found in his second species, 

 A. fritschii*. There is no sign of any such spines in the 

 Crawcrook fossil. 



The comparison breaks down, however, in regard to the 

 limbs. Pocock's figure shows limbs of a normal type in his 

 Anthracosiro woodwardi. If, therefore, the Crawcrook fossil 

 is of the same species, one of three propositions must be true : 

 (i) the forward expansions of the femora must be a character 

 not possessed by all individuals of the species, e.g. something 

 of the nature of a sex character, which is highly improbable ; 

 (2) the expansions must have been broken off in Pocock's 

 example or so indistinctly preserved as to have been over- 

 looked ; or (3) I must have been deceived as to the presence 

 of these expansions in my own specimen. The third supposi- 

 tion is so much the most likely on the face of it that I have 

 tried repeatedly to convince myself of its truth; but I have been 

 driven to the conclusion that the broad flanges of the first and 

 second femora have as definite an existence as any other part 

 of the fossil. In view of this striking point of disagreement it 

 seems impossible at present to regard the Crawcrook arachnid 

 as an example of Anthracosiro woodwardi-^ nor is there enough 

 evidence to declare it definitely an Anthracosiro at all. On 

 the other hand there are good grounds for thinking it may 

 belong to that genus, and -no sufficient reason for putting it in 

 any other. I suggest, therefore, that until further light can be 

 thrown upon its identity it should be known as Anthracosiro 

 latipes. 



* Geol. Mag., 1903, p. 406. 



