Jan. i, 1S85] 



NA TURE 



20 1 



roosts with its snout pointing in the same direction. 

 As might be expected, this direction is only constant for 

 individuals. As the shape of the scar corresponds exactly 

 with the shape of the shell, comfort, of course, could only 

 be gained and a firm hold effected by limpets roosting 

 permanently in the same direction on their scars. 



The question now arises, What sense is employed by the 

 limpet in finding its way back to its scar ? The appreciation 

 of locality displiycd is certainly, for so simply-organised 

 an animal, very keen. The sense of sight is evidently out 

 of court, for an eye like the limpet's, consisting of no more 

 than a sensitive cup, could do little if any more than dis- 

 tinguish between light of different degrees of intensity. 

 The tentacles seemed at first sight to be extremely likely 

 organs to use for the purpose, and to decide this I excised 

 those of two marked individuals which were off their scars. 

 One speedily found its way back : the other seemed 

 confused by the operation for several days, but after that 

 time was found on its scar. This shows a remarkable 

 power of memory, unless the scar was found by accident, 

 which is possible, as the individual was near home when 

 the operation was performed. But even in that case the 

 scar must almost certainly have been remembered. Thus, 

 the tentacles do not seem to be the means by which 

 home is returned to. The sense of smell then suggested 

 itself, and it occurred to me that one reason why limpets 

 kept on their scars when covered by the water was to pre- 

 vent the " scent " of the track traversed from being washed 

 off. With a view to determine this the space between a 

 wandering limpet and its scar and the scar was carefully 

 washed again and again with sea-water. In spite of this 

 the limpet in question readily found its way back again. 

 Further experiments are, however, needed on this head, 

 for any ordinary washing would be very ineffective com- 

 pared with the prolonged soaking the tide would effect in 

 the case of a limpet (like the one just mentioned) living 

 some distance below high-water mark. Still some limpets 

 live so near this last that they are covered but a very 

 short time,_and yet these remain on their scars during 

 that time. Hence I think some other motive probably 

 induces them to remain firmly fixed to their scars when 

 under water. Of course they can hold on best when 

 so fixed, and this suggests the most likely reason for 

 the habit, i.e. to avoid being washed off the rocks by 

 the tide. I am inclined to think that the snout plays 

 some part in helping the limpet to get home, as this organ 

 is extremely sensitive, and certainly plays an important 

 part in discovering suitable food. I intend carrying on 

 more extended observations with a view to the more com- 

 plete elucidation of this puzzling question in regard to the 

 locality-sense, but this preliminary notice may 

 possibly be of some interest. j. R. Davis 



University College of Wales, Aberystwith 



THE MEDITERRANEAN FAUNA* 

 "\7ERV welcome to all zoologists, especially to those 

 * living in Europe, will be the first part of what 

 promises to be a most useful work on the animals known 

 to inhabit the .Mediterranean Sea. For more than 

 twenty-five years I'rof. J. Victor Cams tells us he has been 

 collecting the materials for such a volume, and now that 

 he has to be congratulated on the appearance of so much 

 of it, we trust it may not be long ere we shall be enabled 

 to announce that it is complete. The first part gives a 

 list of the Ccelenterates, Echinoderms, and Worms. The 

 next will treat of the Arthropods, Mollusks, and Verte- 

 brates. The author on mature deliberation resolved to 

 omit from the enumeration the Protozoa and Sponges, 

 not seeing his way to give of these satisfactory detailed 

 diagnoses, and also because, while Haeckel and others 



1 " Prodomus Faunae Mediterranean, sive Descriptio Animalium maris 

 Mediterranei incolamm quam comparata silva rerum quatenus innoluit 

 adjectis locis et nominibus vulgaribus eorumque auctoribus in commodum 

 Zoologorum congessit Julius Victor Cams." Pars 1. Ccelenterata, Echino- 

 dermata, et Vermes. (Stuttgart, 1884.) 



have done a good deal towards increasing our knowledge 

 of the Mediterranean Protozoa, and Oscar Schmidt and 

 others have done the same with the Sponges, yet the 

 groups have not been rigidly systematised in the same 

 way, for example, as the Ccelenterates. 



In the Prodomus, a diagnosis of each sub-order, family, 

 genus, and species is given, with the synonymy of each 

 species, its general distribution, and then its known 

 habitats in the Mediterranean. When the species has 

 been found only in the Mediterranean it is specially 

 marked, the only exceptions we notice to this rule being 

 in the case of the parasitic worms, and from the nature of 

 their hosts they are just as likely as not to be found out 

 of bounds. We have examined the list of the species 

 with a good deal of attention, and have been greatly struck 

 with the immense care that has been evidently used in its 

 compilation. Many of the records and descriptions of 

 these species are not to be found in monographs or special 

 treatises on the fauna of certain well-known bays, like 

 those of Naples, Marseilles, &c, but lie scattered over the 

 numerous pages of our periodical literature, often difficult 

 to be got at ; indeed, in some few cases, we notice the 

 record of the habitat is based on the authenticated 

 examples in museums. In admitting some doubtful 

 species on the authority of authors of good repute, Prof. 

 Cams has acted wisely, for, should it be necessary, .1 

 stroke of a pen would suffice to reduce these to synonymic 

 rank, while, should they be ultimately approved of, they 

 are already in their places. 



This Prodomus is dedicated to Sir Henry Wentworth 

 Acland, K.C.B., who for these long years past has taken so 

 much interest in zoology in connection with Christ Church, 

 Oxford, and who well merits this tribute of respect and 

 confidence from Prof. Cams. Those whose knowledge of 

 zoology in Oxford only dates from the period of the New 

 Museum, and who have no leisure for mastering the 

 details of the past, may not be aware how much the col- 

 lection of zoology and comparative anatomy owes to the 

 labours of Victor Cams, who collected, we believe, for Sir 

 Henry Acland during a great part of 1850, at the Scilly 

 Islands, the series of British Invertebrates then placed in 

 Christ Church Museum, and now Prof. Carus, having 

 taken a larger area within his grasp, associates this Pro- 

 domus of its Fauna with our Oxford Professor, as a sign 

 and token that he has not forgotten those earlier days. 



067? FUTURE CLOCKS AND WATCHES 

 T N connection with what we have said before on this sub- 

 ■*■ ject we give a drawing of the new dial in use on some 

 of the American railways where the new system is already 



at work, the clocks indicating a certain number of hours 

 plus Greenwich, according to the longitude of the section. 



