SCIENCE-GOSSIP. 



most markedly by the nitrogen compounds— atoms 

 of intramolecular systems oscillating between two 

 positions in equilibria, and thereby rendering the 

 whole molecule mobile. The presence of nitrogen 

 in a compound appears to favour the production of 

 this intramolecular motion in a marked degree. It 

 is evident that if nitrogen has this effect in the case 

 of non-living carbon compounds, it will also have 

 the same effect in the vastly more complex proto- 

 plasm, and thus enable a condition of dynamical 

 intramolecular equilibrium to be maintained, thus 

 civing rise to the phenomenon of life. It is significant 

 that all living matter contains nitrogen. I might add 

 here that the indifference shown by living matter to 

 reagents that readily react with dead protoplasm 

 may be explained as due to the stability of a system 

 in motion. While, therefore, I regard nitrogen as 

 the "motion-producing" element, I regard carbon 

 as the " linking" element- the element which binds 

 together the system, and directs and regulates the 

 flow of atoms within the living molecule. Both 

 carbon and nitrogen are, according to this view, 

 equally essential to life ; but it is the carbon, as the 

 "skeleton" element, that must be regarded as the 

 central element of the organism. I have, however, 

 not yet had the pleasure of reading Dr. Allen's 

 work, and consequently might be doing him an in- 

 justice. 



13 Hampton Road, Bristol, 

 March 10th, 1900. 



Dipterous genus Bombylius. — The spring, 

 which will now soon be upon us, is the time when 

 the few British species of Bombylius may be taken 

 over flowers in sunny gardens and hedgerows. These 

 very pubescent, bee-like, short, round-bodied flies 

 with rather long narrow wings, very thin legs, and 

 long fine proboscis, are not common, and are, I 

 believe, chiefly local. B. major, the commonest 

 species, has clear wings with a dark-brown, well- 

 marked fore border. B. discolor Mik. , often mistaken 

 for B. medius, which is probably not a British species, 

 is less common, and is distinguished from B. major 

 by the wings being prettily sprinkled with small 

 brown spots and the absence of the brown border. 

 It differs from B. medius by the hair at tip of abdo- 

 men being quite black, not yellow like the rest of the 

 body, as is the case in B. medius. The other two 

 species are easily known from both the above by- 

 being much smaller and having unmarked wings ; 

 B. carescens is distinguished from B. minor by having 

 long instead of short hair behind the head. — E. 

 Brunetti, Strand, London, IF. C. 



Wasps Eating Set Insects. — Mr. Stoyefs 

 note referring to wasps eating insects on the setting- 

 boards reminds me that this occurred once with me 

 dining my first year's collecting, when Lused to set 

 all my specimens. I had captured in Kent a male 

 and female in copula of a large species of Asilus, 

 either Eutohnus rujibarbis or Machimus rusticus, 

 and an hour or two after setting them in the usual 

 way I found, to my disgust, that two or three wasps, 

 which were still eating, had entered the open window 

 and devoured the best part of the bodies of both 

 insects. — E. Brunetti, Strand, London, W.C., 

 March 1900. 



AN INTRODUCTION TO 

 BRITISH SPIDERS. 



By Frank Percy Smith. 



{Continued from page 310.) 



FAMILY OONOPIDAE. 



T"*H'E spiders included in this family are very 

 -*■ different in general appearance from the 

 Dysderidae, although the arrangement of the eyes 

 bears some resemblance to that of the genus Dysdera. 

 The spiracular openings are very indistinct, and it is 

 stated on good authority that there are two only. 

 One genus is found in Britain, and that containing a 

 single species. 



GENUS OONOPS TEMPL. 



In this genus the eyes are closely grouped and are 

 of considerable size. The single known British 

 species is not at all common. 



Oonops pulclisr Tempi. 



Length. Male 1.8 mm., female 2 mm. 



Cephalo-thorax, legs and abdomen of a red colour. 

 The palpal organs are simple in structure. This 

 active little spider may be looked for in the spring. 

 It is not common, but is found in very varied 

 situations. 



FAMILY SCYTODIDAE. 



The spiders included in this family are mostly 

 inhabitants of warm countries, one species only being 

 found in Britain. The eyes are arranged in three 

 pairs which form a triangle, with apex in front. 



GENUS SCYTODES LATR. 



The cephalo-thorax is of most remarkable form, 

 its hinder portion being greatly elevated. The legs 

 are fairly long and rather weak. Relative length 

 4- 1, 2, 3. 



Scytodes tlioracica Latr. 



Length. Female 8 mm. 



Cephalo-thorax yellow, marked with blackish- 

 brown ; legs yellow, slightly annulated ; abdomen 

 pale greyish-yellow, marked with blackish-brown... 

 The palpal organs are extremely simple in structure. 

 This spider is found, though very rarely, in buildings 

 of various kinds. 



FAMILY DRASSIDAE. 



This family includes a large number of spiders, 

 mostly of dull hue and indistinctly marked. The 

 eyes, eight in number, are arranged in two transverse 

 rows on the front part of the caput. The cephalo- 

 thorax is usually somewhat depressed. The tarsal 

 claws are two in number, and the legs are provided 

 with spines. The abdomen is usually of a more or 

 less cylindrical form. 



GENUS PROSTHESLMA L. KOCH. 



This genus contains a number of black or blackish- 

 brown spiders, which may be distinguished from 



