March 24, 1893.] 



SCIENCE. 



157 



advantaged the possessor to such extent that not infrequently life 

 has been preserved by it. It is reasonable to assume that the 

 parts have not become so widely unlike in pereeptiveness wiihout 

 some cause, and, if the cause alleged is natural selection, it be- 

 comes necessary to show that the greater degree of the power 

 possessed by this part than by that has conduced so much to the 

 maintenance of life that an individual in whom a variation had 

 produced better adjustment to needs, thereby maintained life 

 when some others lost it, and that among the descendants in- 

 heriting this variation there was a derived advantage such as en- 

 abled them to multiply more than the descendants of individuals 

 not possessing it. Can anything like this be shown ? 



That the superior pereeptiveness of the forefinger-tip has thus 

 arisen, might be contended with some apparent reason, as such 

 pereeptiveness is an important aid to manipulation. But how 

 about the back of the trunk and its face, or the tip of the nose, 

 or the thigh? The survival of the fittest cannot explain these 

 diff-rences of pereeptiveness. But if there has been in operation 

 a cause which it is now the fashion to deny, the various differ- 

 ences are at once accounted for. This cause is the transmission 

 of inherited traits or characters. 



(Here Mr. Spencer records some experiments which show that 

 constant exercise of the tactual nervous structures leads to fur- 

 ther development, to greater discriminativeness. The pereeptive- 

 ness of the finger-ends of the blind who read from raised letters 

 and of compositors is greater than that of the finger-ends of other 

 people.) 



Now. if acquired structural traits are inheritable, the gradations 

 in tactual pereeptiveness are the result of the gradations in the 

 tactual exercises of the parts. The trunk has but little converse 

 with external bodies, and it has but small discriminative power; 

 what power it has is greater on its face than on its back, corres- 

 ponding to the fact that the chest and abdomen are more fre- 

 quently explored by the hands, this difference being probably in 

 part inherited from inferior creatures. The middle of the fore- 

 arm and the middle of the thigh are obtuse, having rare experi- 

 ence of irregular foreign bodies. The tip of the nose has con- 

 siderable tactual experience, hence its greater pereeptiveness. 

 The inner surfaces of the hands are more constantly occupied in 

 touching than are the back of the hand, breast, forearm, fore- 

 head, while the tips of the fingers come into play not only when 

 things are gra>ped, but when things are felt at or manipulated. 

 If then it be that the extra pereeptiveness acquired from extra 

 tactual activities, as in a compositor, is inheritable, the grada- 

 tions of tactual pereeptiveness are explained. 



The tip of the t mgue exceeds all other parts in power of tactual 

 discrimination; why such pereeptiveness? Its functions of mov- 

 ing food during mastication and of making many of the articula- 

 tions constituting speech, are not materially aided by extreme 

 pereeptiveness. and natural selection cannot have caused it. But 

 assume inheritance of acquired traits, and there is no difficulty, 

 for the tongue-tip has, above all other parts of the body, increas- 

 ing experiences of small irregularities of surface. It is in contact 

 with the teeth, and either consciously or unconsciously is con- 

 tinually exploring them. There is hardly a moment in which 

 impressions of adjacent but different portions are not being 

 yielded to it by either the surfaces of the teeth or their edges. 

 No advantage is gained ; it is simply that the tongue's position 

 renders perpetual exploration almost inevitable; and by perpetual 

 exploration is developed this unique power of discrimination. 



Thus the law holds throughout, from this highest degree 

 of pereeptiveness of the tongue- tip to its lowest degree on the 

 back of the trunk; and no other explanation of the facts seems 

 possible. 



But some biologists might contend that panmixia affords an 

 adequate explanation of the facts. So Mr. Spencer, after pointing 

 out that the explanation by panmixia implies that these grada- 

 tions of perceptivene.-s have been arrived at by the dwindling of 

 nervous structures, and hence makes an unproved and improbable 

 assumption the basis of the argument, proceeds to establish that, 

 even with this objection passed over, it may with certainty be de- 

 nied th?A ixnimixia can furnish an explanation. As this part of 

 the essay is left unfinished, it would be unwise to attempt an 



abstract of the Spencerian criticism of the pawnijarfa explanation. 

 We shall return to the subject as soon as Mr. Spencer brings his 

 argument to a close. 



FEEDING-LINKS OF A LIVING LAND 6ASTER0P0D ON 

 LICHENED SLATE. 



BY J. B. WOODWOKTH, SOMERVILUE, MASS. 



In searching for fossils in the Carboniferous rocks of Atllelx)ro, 

 Mass., about three years ago, I found on the surface of a vertical 

 stratum of micaceous slaty sandstone, in an old quarry, what 

 at first glance appeared to be annelid trails resembling the form 

 known bs Ner sites common in the Silurian. Further examination 

 showed me at once, however, that these markings were caused 

 by the gnawing away of a drab-colored crust of lichens and dust 

 which concealed the r-eal appearance of the rock. The trails 

 were in the form of bands about one-quarter of an inch wide, 

 wandering over the surface of the outcrop, or curved back and 

 forth on each other, so as to approach but rarely cross. These 

 bands or trails were made up of a series of crescentic cross- 

 markings united alternately right and left with the next adjacent 

 in the series so as to form a continuous, closely pressed, sigmoid 

 line, which in itself constituted the whole of the trail. The trail 

 was evidently the feeding-line of some animal. Another occur- 

 rence which I have more recently observed in Bristol County, 

 Mass., exhibited a trace of slime along the feeding-line, such as 

 is left by slugs or land snails, thus showing that the feeder was 

 probably a gasteropod. 



Ebenezer Emmons, in the Agriculture of New Yorlc, Vol. I., 

 1846, p. 68, describes a trail found upon the surface of the fine 

 green slate of Salem, Washington Co., N. Y., included in his 

 "Taconic System," to which he gave the name Nemapodia tenu- 

 igsima. The figure of this trail on pi. 14. fig. 1, of that work, 

 agrees closely with the Attleboro trails. In an explanatory note, 

 p. 365, Emmons states that this trail has been shown, he thinks, 

 satisfactorily by his friend Dr. Fitch, "to be formed by some 

 living unknown animal." It seems to me highly probable that 

 the trail observed by Emmons, and shown to be not a fossil 

 by his friend Dr. Fitch, was also that of a gasteropod. Concholo- 

 gists may be familiar with the animal which makes these tracks, 

 if I am right in thinking that they are made by gasteropods at 

 all. As yet I have been unable to catch the animal at its work. 



NOTE ON THE GENERIC NAME CHIROTES. 



BY LEONHABD STEJNEGBR, CUKATOR DEPT. REPT. AND BATR., TJ. S. 

 NAT. MUSEUM, WASHINGTON, D.C. 



The application of the law of priority necessitates the aboli- 

 tion of Cuvier's name Chirotei for the " Two-handed Ground 

 Worm." No less than three generic names, formally proposed 

 and diagnosed, have priority over CMrotes, none of which is pre- 

 occupied, and which in turn would have to be adopted, should 

 any of the older ones for some reason become unavailable. 



Bonnaterre seems to have been the first to give a Latin name 

 toLaCepede's Cannelee, and to recognize its generic distinct- 

 ness. However, by sheer carelessness he neglected to do so and 

 a solitary "S" stands for the generic name he intended to im- 

 pose. It may be assumed that he meant to call it Bipes, but 

 we have nothing to do with assumptions. At the same time he 

 included as the second species of his intended genus, Pallas's 

 Lacerta apms, under the name B shelto-pusiJc. 



Latreille, however, saw the incongruity of uniting the two in 

 the same genus, and expressly restricted ' the name Bipies to the 

 B. canaliculatus. The genus was thus formally established, 

 named, diagnosed and restricted in 1802 as Bipes. Bonnaterre's 

 other species he made a separate genus, Shcltopusik,' renaming 

 Pallas's species Sheltopvsik didactylus.^ The latter will therefore 

 stand as Sheltopmsih cqma (Pall.). It will be observed that this 



1 " Xous ne connoissons encore qu'une seule esp^ce blen distincte de C6 

 genre." 



» Latreille, Hist. Nat. Kept., II., 1802, p. 871. 

 3 Latreille, torn, clt., p. 273. 



