266 Mr. B. F. Cummings on the 



XXX. — Note on the Crop in the Mallophaga and on the 

 Arrangement and Systematic Value of the Crop-Teeth. By 

 Bruce F. Cummings. 



(Published by permission of the Trustees of the British Museum.) 



During an examination for description * of the interesting 

 parasite Trimenopon eclunoderma, Cummings, a row of 

 strongly developed teeth was observed in specimens passed 

 through caustic potash and mounted in Canada balsam, 

 occupying a position in the abdomen at about the level where 

 the proventriculus might be deemed to lie. Reference to 

 Snodgrass's paper f on the anatomy of the Mallophaga 

 showed that no proventriculus has been found to exist in this 

 order. On dissection it became quite clear that in fact no 

 portion of the base of the crop (or ingluvies) is constricted off 

 as a gizzard either in the Ischnocera or in the other suborder, 

 the Amblycera. Yet the base of the crop of the Amblycera 

 in the genera Heterodoxies, Trimenopon, Losmobothrium, 

 Colpocephalum, Menopon, Trinoton, Boopia, Nitzschia, and 

 Gyropus, and probably in the remaining genera, possesses a 

 circular row of beautiful proventiicular teeth, so that, func- 

 tionally, a proventriculus may be said to be present in this 

 suborder. There are scattered teeth in the crop of the 

 Ischnocera, but they occupy a different area of the crop, 

 which in the Ischnocera is highly specialized. 



The crop presents three types of structure in the Mallo- 

 phaga. One form — the Amblyceran — is simple in being- 

 just an expansion of the lower part of the oesophagus. The 

 second, represented by the majority of the Ischnocera, 

 iSnodgrass describes as complicated by a lateral and back- 

 ward prolongation, so as to form a large expanded diverticulum 

 of the oesophagus. The third type, present in the Ischno- 

 ceran family Triehodectidse, has" the remarkable form of a 

 large sac connected with the lower end of the oesophagus by 

 a long narrow neck. 



Morphologically the crop is simply an expanded portion of 

 the oesophagus. It is large in locusts and most other 

 Orthoptera and in most adult Coleoptera. It may or may 

 not be followed by the proventriculus, which is present and 

 well developed in many carnivorous Coleoptera, in fleas, ants, 

 and Cynips. In fact, the alimentary canal is a notoriously 

 unsafe guide in phylogeny, although the arrangement of the 

 teeth in the proventiiculus has been used systematically in 



* Bulletin for Entomological Research, May 1913. 

 t Occas. Papers Cal. Acad, of Sci. vi. 1899, p. 145. 



