470 



NA TURE 



[_Sept. 1 6, 1880 



a deep-water mussel of considerable size, whicli I propose to 

 name Mytilus liiteus. It inhabits the layer of mud which I 

 have above described, and moors or fixes itself by means of a 

 large and densely-matted byssus which is spun by the foot. 

 This byssus is capable of being spread over a considerable 

 extent of surface ; and it not only prevents the mollusk sinking 

 Into the soft mud and being smothered or buried alive, but 

 enables it to feed comfortably on the innumerable animalcula 

 which swarm on the surface of the sea-bed. It is of the same 

 use to the- mollusk as the snow-shoe is to the Arctic tr.aveller. 

 This species of Mytilus I at first took to be the Modiola 

 iiiciirvata of Philippi — M. martoreUi of Hidalgo, which lives 

 on the south coast of Spain in rather shallow water ; but on 

 comparison I am satisfied that they differ essentially in shape, 

 ■sculpture, colour, and epidermis. 



I cannot conclude this account without acknowledging my 

 most grateful thanks to the French Government for their 

 extremely generous conduct in my case and for the excellent 

 hospitality which I enjoyed on boaid the Travailleur, as well as 

 to the President and Members of the Scientific Commission for 

 their obliging and friendly companionship. 



The zoological results of this French Expedition are fully 

 equal to those made by Capt. Baudon in iSoi, M. d'Urville 

 In 1829, the Rcche)-che in 1S35, the Astrolabe in 1841, and other 

 French expeditions ; and I sincerely hope that a further expedi- 

 tion of the present kind may take place next year in the 

 Mediterranean, where our good and gallant neighbours have 

 such an important stake. 



The list of MoUusca referred to in this paper includes the 

 following new species named or recoo;nised by the author : — 

 Pecieu oMiquatiis, Lima Jeffrey si (Fischer), Mytilus luteiis, 

 Modiolaria cuneata, Axinus tortuosus, Mytilimeria (?) Fischeri, 

 Thraeia tenera, Cadnliis semistriatiis, Rimiila astnriana, Odo- 

 stomia lineata, and Bitllina clongata. The species which he 

 T:onsiders peculiarly northern are Chiton alveolus, G. O. Sars, 

 Fusus turgidulus, Jeffreys, and Pleiirotoma nivalis, Loven ; and 

 the species which he considers peculiarly southern or Mediter- 

 ranean is Odostomia fasciatus, Forbes. 



THE SHOWER OF AUGUST PERSE WS, 18S0 

 'X'HE August meteors were observed under peculiarly favour- 

 able cu-cumstances this year. Not only was the moon 

 entirely absent during the display, but the weather, which fo 

 frequently interrupts such observations, remained fine night after 

 night, thus allowing an unbroken series of watches to be main- 

 tained from the 6th to the 13th, and enabling the rise and fall of 

 the display to be distinctly traced from a comparison of the 

 results obtained each night. On the loth, however, when the 

 maximum was expected, the state of the sky scarcely admitted 

 of successful observation, and the number of shooting-stars 

 recorded that night was below the experiences of past years, but 

 it must be remembered that, this being leap year, the chief in- 

 tensity of the shower was due earlier than usual, so that it may 

 Iiave occurred liefore the evening of the loth, when observers 

 generally were watching for its reappearance. 



At Bristol the following summary was derived from observations 

 by the writer : — 



The observed maximum occurred on the 9th, when, during a 

 watch of 2j hours, meteors were falling at the rate of 44 per 

 Tiour (for one observer), and the {proportion of Perseids was 

 nearly two-thirds of the aggregate number visible. On the loth 

 the horary number of 34 was determined under less favourable 

 <:onditlons. A fog partially overspread the sky, rendering the 



stars dim, so that many small meteors passed unrecorded, and at 

 1 1 .Vh. it was found impracticable to continue observations. The 

 horary number of Perseids found on the loth coincides with thit 

 of the preceding night, and it is obvious that, allowing for tte 

 clearer atmosphere of the gth, the maximum of the display realy 

 occurred as usual on the loth. It is fan to assume from the 

 numbers actually counted in the fog-shrouded sky of the loth 

 that later in the night, as the radiant attained greater elevation, 

 the meteors from Perseus were as numerous as during the few 

 preceding apparitions of the shower. The brightest meteor ob- 

 served at Bristol appeared at I3h. 37m., on August 8. The sky 

 had become overcast except near the western horizon, where a 

 few stars could still be distinguished. A vivid flash startled the 

 observer, who, on looking towards the direction indicated, at 

 once saw a brilliant meteor streak attached to the star 7 

 Ophiuchi, and its position was such as to leave no doubt that it 

 had been left by a magnificent Perseid. Other large meteors 

 were registered as follows ; — 



These meteors all belonged to the shower of Perseids. Motions 

 very swift. They all left bright streaks. 



The radiant point showed a displacement on nearly every suc- 

 cessive night of observation. It was noted at 38° + 56° on the 

 6th, yet on the 13th a few meteors indicated it very exactly at 

 49i° + 57i°- This corroborates observations made by the -ivriter 

 in 1877, and reported in Nature, vol. xvi. p. 362. A large 

 number of Perseids were seen that year, and from an exact record 

 of their flights the radiant point was seen to advance in R.A. as 

 follows : — 



a i 



1B77, August 3-7 = 40° -I- 56° 

 10 = 43° + 53° 

 12 = 50, + 56" 

 16 = 60' + 59° 



This is further borne out by Mr. Heni7 Corder's extensive 

 observations at Writtle, near Chelmsford, during the recent display, 

 \\ hich may be tabulated as under : — 



Mr. Corder places the average position of the radiant of the true 

 Perseids at 45° + 58°. On the first few nights of August he 

 found it well defined at 35° + 56°, though on the nth it had 

 apparently shifted to 46' + 58°. And it is to be remarked that 



