300 



SCIENCE. 



[N. S. Vol. XII. No. 295. 



Some Cases of Saltatory Variation : By C. H. 

 EiGENMANN and Ulysses Cox, Indiana 

 University. 



1. A specimen oi Rana pipiens 54 mm. long 

 has the forearm and hand of the right side 

 duplicated. This arm is carried in a sling 

 formed of a loop of the skin of the breast 

 4 mm. wide. This is a pathological abnor- 

 mality rather than a variation that leads 

 to the mutation of species. 



2. A specimen of ^meiwrMS natalisVlO mm. 

 differs from normal specimens in the total 

 absence of all traces of the ventral fins. 

 This is a saltatory variation which if pre- 

 potent might give rise to a race of catfish 

 without ventrals, which would be consid- 

 ered generically different from the parent 

 stock. This specimen is of interest in con- 

 nection with the next case. 



3. A variation of great importance and 

 no small interest is presented by nine speci- 

 mens of Ameiurus vielas. These were col- 

 lected at random from among a large num- 

 ber in Mitchell's Cave, Kentucky. Each 

 one possesses one or more supplemental 

 nasal barbels. These might give rise to the 

 supposition that they are the direct result 

 of the cave life, but an examination of all 

 the data makes it probable that we are 

 dealing with a coincidence of a cave habitat 

 and a prepotent saltatory variation that ap- 

 pears adaptive to a cave existence. The con- 

 clusions arrived at concerning these speci- 

 mens are : (1) the variation is saltatory. 

 (2) it is bilateral without reaching perfect 

 bilateral correlation ; (3) it is improbable 

 that the variation arose independently in 

 each of the specimens ; (4) the variation 

 probably arose in one of the ancestors of 

 the specimens ; (5) admitting (4) the salta- 

 tory variation arising in an ancestor was 

 prepotent to a very high degree. 



Variation and Correlation in the Tibial Spines 

 of Melanoplus : By C. B. Davenport, 

 University of Chicago. 



This paper, embracing work done in con- 

 nection with Miss Ora H. Hubbard gives 

 the constants and their probable errors 

 of the distributions of frequencies of the 

 spines of the inner and outer rows of spines 

 on the right and left-hand tibise of Melano- 

 plus fetnur-ruhruni from Newport, Rhode 

 Island. The correlations of the number 

 of spines in the various rows was de- 

 termined quantitatively and the interesting 

 result obtained that there is a greater 

 correlation between rows symmetrically 

 placed with reference to the plane of sym- 

 metry of the whole animal than there is 

 between rows so placed with reference to 

 the plane of symmetry of the single leg. 

 Finally the range of individual variation is 

 greater than the range of variation of the 

 modes of various species of the genus 

 Melanoplus; consequently in the individual 

 variation of the one species there is pro- 

 vided material for the various typical num- 

 bers of spines found in all species of the 

 genus. 



Variation in lo : ByC. A. Adams. To be 

 published in full. 



On the Origin and Distribution of Leptino- 

 tarea decem-lineata Say, and the part that 

 some of the Climatic Factors have played in 

 their Dissemination: By W. L. Tower, 

 University of Chicago. To be published 

 in Science. 



A Neiu Eyeless Isopod Crustacean from Mexico : 

 By A. S. Packard, Brown University. 

 Some years ago I received through the 

 kindness of Professor A. L. Herrera, of the 

 City of Mexico, an isopod crustacean taken 

 from a well at Monterey, Mexico. It ap- 

 pears to be a true Conilera, and may be 

 named Conilera stygia. 



It is totally eyeless, and adds another to 

 the blind fauna of our caves and wells. 

 Hitherto the genus has been represented by 

 but a single species, inhabiting the British 

 coasts. Compared with Bates and West- 



