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XXXIX. — Remarks on the Falces and MaocillcB of Spiders. 

 By John Blackwall, F.L.S. 



[Plate X. figs. 1, 2, 3.] 



Spiders usually have the groove which is situated on the inner 

 surface of the basal joint of the falces, and receives the terminal 

 joint, or fang, when in a state of repose, armed on each side, to 

 a greater or less extent, with conical, pointed processes which, 

 by a figure of speech, are commonly denominated teeth ; but 

 that they are not the homologues of true teeth is rendered suffi- 

 ciently evident by the fact that the falces do not constitute any 

 part of the oral apparatus, being lethal instruments employed 

 by the Araneidea in seizing, killing, and compressing their 

 prey. 



Eminent arachnologists have stated that the species belonging 

 to extensive divisions of the family Mygalida are entirely desti- 

 tute of tooth-like processes on the basal joint of the falces ; but 

 the fallacy of this opinion may be easily detected by a careful 

 inspection of specimens taken from the genus Mijgale, the most 

 typical division of the family. In confirmation of the fact that 

 many of the Mygalidce are provided with a longitudinal row of 

 tooth-like processes, situated between two dense fringes of long, 

 curved, red hairs on the inferior surface of the basal joint of 

 their falces, various examples might be adduced; but it will 

 suffice on the present occasion to name the My gale ursina of 

 Koch, the Mygale zebra of Walckenaer, and the Atypus Sulzeri 

 of Latreille, 



Near the extremity of the outer margin of the maxillae of nu- 

 merous species of spiders there is a slight dark-coloured ridge, 

 surmounted by a series of extremely minute close-set spines, 

 which I have long known and regarded as contributing to give 

 firmness to the most exposed part of those organs, and as afford- 

 ing some assistance in restraining the action and in the reten- 

 tion of the insects on which such spiders prey. Miss Staveley, 

 on examining this structure under a high degree of magnifying 

 power, has arrived at the conclusion that it maybe resolved into 

 a row of minute teeth (Ann. & Mag. Nat. Hist. ser. 3. vol. xvii. 

 p. 399) — an opinion which its connexion with the maxillae would 

 probably tend to suggest; by its position and conformation, 

 however, it appears to be little, if at all, adapted to aid in the 

 office of mastication. 



As the maxillae of those species of the family Mygalida that 

 have the palpi articulated at or near their extremity might be 

 expected to present other modifications of structure, it became 

 an object of some interest to subject them to a careful examina- 

 tion ; with this view, I dissected several specimens of the Myga- 



