676 SUMMARY OF CURRENT RESEARCHES RELATING TO 



The rbabdomeres, which all agree in regarding as the receiving termina- 

 tions for luminous impressions, consist of two portions placed in line 

 with each other. There is a short terminal highly refringent and 

 homogeneous rod situated in the cavity between the pseudocone and the 

 pigmentary iris. There are seven (not six as Hickson has stated) rods 

 united in a fascicle with fixed relations which are the same for all the 

 ommatidia of the same region of the eye. These rods are continued as 

 a long and more slender stalk in the deep layer, and these possess a 

 heterogeneous structure analogous to that which characterises all the 

 photo-receptive elements, including the cones and rods of the Vertebrates. 

 The seven rhabdomeres of the ommatidia remain distinct ; they belong 

 to seven retinular cells, each of which emits a conducting fibre into the 

 deep cells. 



Sac surrounding Pupas of Ichneumonidse.*— J. E. Y. Boas de- 

 scribes a peculiar sac within which were pupffi of an ichneumon-fly 

 Anomolon circumflexum L. parasitic on pine-moth pupas. The parasite 

 was found inside the empty chitinous husk of the pupa, and within the 

 cocoon, investing it closely, was a gelatinous brownish sac filled with a 

 dark brown fluid. The sac was invaginated at one end to receive the 

 large abdominal portion of the pupa. Full grown larvas were sometimes 

 found in similar sacs, and an examination of larv» at all stages showed 

 that the sacs were the contents of the intestine inclosed in the lining 

 membrane of the mid-gut, and expelled towards the close of larval life. 

 Analogous faecal sacs are expelled by many insects, but the turning of 

 the sac to account as a protective cushion for the pupa has not hitherto 

 been observed in regard to any other form. 



Structure of the House-fly .f—C. G. Hewitt, in the first of three 

 papers on the structure, development, and bionomics of Musca domestica, 

 deals with the anatomy of the insect, of which no complete account has 

 hitherto been published. On morphological grounds, the author adopts 

 the view that the distal portion of the proboscis represents the modified 

 second maxillas or labium, and is not derived from the first maxillae. 

 The traclieal system is described with special minuteness. There are 

 two thoracic spiracles, the first supplying the whole of the head, the 

 anterior and median regions of the thorax and the three pairs of legs, 

 and, by means of air sacs, a large part of the viscera. The second 

 supplies the muscles of the median and posterior region of the thorax. 

 There are seven pairs of abdominal spiracles in the male, and five in the 

 female. The extension of the proboscis is believed to be due to the 

 inflation of the tracheal sacs of the head and rostrum, and that of the 

 oral lobes, which contain only annulated trachese, is probably effected by 

 blood-pressure. 



New Hercules Beetle.^ — A. H. Verrill gives some notes on 

 Dynastes hercules and other beetles collected on Dominica island. 

 Variations in colour and markings are so numerous and grade so 

 imperceptibly into one another that it is not . possible to distinguish 



* Zool. Jahrb., xxv. heft 2, pp. 321-7 (1 pi.). 



t Quart. Journ. Micr. Sci., li. (1907) pp. 394-448 (5 pis.). 



X Amer. Journ. Sci., clxxiv. (1907) pp. 305-8. 



