390 SUMMARY OF OUHRENT KESEARGllES RELATING TO 



5. Arachnida. 



Critical Study of Sarcoptes. — Cecil Waeburton {Parasitology, 

 1920, 12, 26r)-;:)00, 1 pi.)- It is probable that Cnemidocoptes from 

 l)irds and Notmires from small mammals will be fomid to be generically 

 distinct from Sarcoptes, but it is necessary to revise the various form's 

 of Sarcoptes — e.g. as to clijfitotaxy and armature — to see whether there 

 are distinct species in the genus. These should be transferred from 

 one host to another to see what difference may be thus brought about. 



J.A.T. 



Capitulum of Psoroptes.— P. A. Buxton {Parasitology, 1920, 12. 

 234-(), 2 figs.). A careful description of the capitulum and mouth- 

 parts of Psoroptes equi. The mite carries its head tucked down between 

 the bases of the first pair of legs. The chelicera? are extremely small 

 and colourless. It may be assumed that the mite obtains a secure hold 

 on the skin of its host by aid of its ambulacra and tarsal claws, and that 

 it then steadies itself by applying the finger-like processes closely to the 

 skin. It would then bring the cheliceras into action, probably using 

 '■ setae 1 and 2 " as organs of touch. J. A. T. 



f- Crustacea. 



Eyes of a Cave Decapod. — W. Harms {ZooL Anzeiger, 1921, 52. 

 101-15, 7 figs.). A study of a Galatheid, Munidopsis polymorpJur 

 Koelbel, from a Lanzarote cave (Canaries). The colour is translucent 

 white ; the animal hides quickly under stones : the compound eyes are 

 difficult to see ; there are no corneal facets, and the cornea itself is 

 degenerate, and may be represented only by a few cells. There is 

 considerable individual variation in the eye, and two types — more or 

 less reduced — can be distinguished. The minute structure is described. 

 Tliere can be no vision, but doubtless a perception of light and shade. 

 Crystalline cones persist, probably in adaptation to some light that 

 enters by the f alien-in roof of the cave. The other species of Munidopsis 

 are in the deep sea. J. A. T. 



Aunulata. 



Nerve Cord and Spindle Muscle of Physcosoma. — ^V. Harms 

 {Zool. Anzeiger, 1920, 22, 67-7G, 8 figs.). In a species of this 

 Sipunculid, very abundant at Lanzarote, there is extraordinary power of 

 longitudinal contraction. In association with this there is a coiling of 

 the nerve cord into a close spiral, especially in the proboscis region. 

 The spindle muscle which runs freely from the posterior end of the 

 body, along the spirally twisted gut, to a point immediately in front of 

 the anus, is also adapted to the extreme contraction. The fibres assume 

 a remarkable corkscrew appearance. Both nerve cord and spindle muscle 

 retain their position parallel to the long axis of the body. An account 

 is given of the details of the contraction in both the nerve strand and 

 the spindle muscle, but the important point is the corkscrew disposition. 



J. A. T. 



