110 BRITISH TYROGLYPHIDJ]. 



paired nerves springing from the sub-oesopliageal 

 ganglion (in Thi/as there is an azygous recurrent nerve 

 between the two). This pair of nerves certainly 

 served the genitalia, and possibly also some of the 

 other organs of the abdomen ; they had several 

 branches : I called them the genital nerves, and I have 

 preserved that name in the present family. 



Anterior to the pair of nerves serving the first pair 

 of legs is another pair of nerves springing from the 

 sub-oesophageal ganglion, making six pairs in all ; they 

 arise from the two anterior projections shown in PL A, 

 fig. 8. Nalepa says they serve the mouth organs ; but 

 he does not mean the mandibles, for he expressly says 

 that these are innervated from the supra-cesophageal 

 ganglion ; apparently he does not mean the palpi, for 

 he says that these also are innervated from the supra- 

 oesophageal ganglion ; although I doubt the correctness 

 of this ; there therefore only remain the maxillse and 

 the lingua; but the former are soldered together to 

 form the maxillary lip or hypostome, and the lingua is 

 very slightly developed in the Tyroglyphidse. I 

 cannot say that I could trace the course of these nerves 

 in the Tyroglyphida3, but I have little doubt that 

 Nalepa is right in saying that they innervate the 

 maxillae, because in Sdella the homologous pair of 

 nerves certainly does so ; but it also in that genus 

 innervates the palpi ; as the palpal branch is much 

 larger than that to the maxillary lip I called the nerve 

 the palpal nerve. It must be remembered that the 

 palpi in the Acari are maxillary palpi, and spring from 

 the maxillary lip ; they are not labial palpi ; it would 

 therefore seem to be improbable that the maxillae should 

 be innervated from the sub-cesophageal and the 

 maxillary palpi from the supra-cesophageal ganglion, 

 and it certainly is not the case in BdeUa. In Tliyas 

 the same nerve sends branches to both organs; but 

 that nerve arises from just where the two ganglia may 

 be supposed to join, and the fusing of the two is so 

 complete that it would not be possible to say which 



