HARDWICKE'S SCIENCE-GOSSIP. 



225 



TEETH OF FLIES. 



HOUSE-FLY No. (2). I^Musca domestica.) 



By W. D. Harris, Cardiff. 



No. n. 



MESSRS. KIRBY & SPENCER in their intro- 

 duction to Entomology mention in the chapter 

 devoted to "direct injuries caused by insects" a 

 species of fly descril^ed by De Geer as '■'■ Musca 

 doDiestica minor,'" and the same authorities assert 

 that he was " one of the most accurate observers 

 that ever existed." We may therefore safely conclude 

 that the flies which pass current as house-flies differ 

 in kind, notwithstanding tlieir great similarity. It 



When, however, we come to examine the teeth, a 

 very decided distinction is immediately apparent, and 

 is a striking instance of the usefulness of these organs 

 as a means of separating species so nearly resembling 

 each other. 



In the present example there are six teeth in each 

 lobe of the proboscis, these are of two different types. 

 The two marginal teeth are distinctly of the blow-fly 

 pattern, while the four intermediate ones are serrated 

 throughout, and terminate in a simple wave-like form 

 quite unlike iMicsca minor, which possesses a distinct 

 central apex in each of the three teeth, in addition to 

 being similarly serrated. 



Both figures are drawn to same scale, viz. one inchj 

 representing three thousandths of an inch. 



Fig- 128. — Teeth of House-fly {Musca domestica) (scale of loooth of an inch). 



was not, however, until I undertook the investigations 

 which form the subject of the present notes that I 

 became so thoroughly convinced of this fact. 



The sketch of the teeth of the house-fly which 

 formed the subject of number one of this series, should, 

 I believe, have been described as Musca domestica 

 minor, while the illustration which accompanies these 

 notes refers to the common house-fly ordinarily 

 accepted as JMusca domestica. In general appearance 

 they are very much alike, but the latter is slightly 

 more robust in structure. Musca minor has a trifle 

 more white on the face ; with this exception the latter 

 might be easily mistaken for a stunted or dwarfed 

 individual of the former species. 



GOSSIP ON CURRENT TOPICS. 

 By W. Mattieu Williams, F.R.A.S. 



MUCH encouragement to the promoters of 

 technological education is derivable from the 

 experience of the Swiss watch trade which has been 

 artificially fostered with wonderful success, not by 

 protectional tariffs, nor liy exportation bounties, but 

 by educating the workmen in such wise that they 

 shall be able to compete successfully with their rivals 

 in spite of serious natural disadvantages. Horo- 

 logical colleges have long been established as public 

 institutions. The first of these was founded in 1824 



