SECOND REPORT OF THE DIRECTOR 1905 



37 



An organism of singular interest and novelty, derived from the 

 lower Portage or Cashaqua horizon at Hunt's quarry, Interlaken, Sen- 

 eca county, is a large starfish of the genius Helianthaster, a form not 

 before known in America, but recognized by two species in the Devon- 

 ic of Germany. In the known species the number of arms does not 

 exceed 16. The Interlaken specimens have 24 or 25 arms and 

 expose the ventral surface, each ambulacral joint bearing a single 

 pair of spines. The body has been largely destroyed in the speci- 

 mens so far seen and in this respect these are like those already 

 described. Other examples of the species will be searched for 

 preparatory to giving a fuller account of this interesting animal. 



Special problems 



Caverns. Interesting features of the geologic structure of 

 New York are its caverns. These are phenomena which have re- 

 ceived only occasional and slight consideration and yet in their 

 formation a number of important problems are involved. It is 

 not generally known that these caves in New York are not alone 

 numerous but some of them extensive and beautiful. Occa- 

 sioned by the faulting in extensive limestone regions, the solvent 

 and erosive power of underground streams has been the funda- 

 mental cause of their existence; the same agent has served to 

 decorate and ornament these caverns with deposits of limestone 

 in the form of stalactite and stalagmite. The study of caverns 

 has become a special branch of scientific interest and there are 

 now organized societies in different parts of the world carrying on 

 these spelean investigations and devoted to the so called science 

 of speleology. 



The geologic processes and results concerned are not altogether 

 simple and uninvolved. Such work beneath the surface when car- 

 ried out to an extreme leads to modifications of the surface topog- 

 raphy, to the formation of natural bridges, sink holes, basins and 

 circumscribed valleys or Karsten. The hydrologic problems based 

 on the course of underground water flow are important, and of the 

 highest interest, indeed attracting at present a lively activity is 

 the study of the biology of caves, the effect of the darkness and 

 attendant surroundings of cave conditions in modifying the sense 

 organs and the coloring of animals. 



In New York the principal region of such caverns is the exten- 

 sive limestone formation constituting the Helderberg Mountain, 

 wherein some of the rock strata are of a high degree of purity 

 which facilitates their easy solution. Largest of all these natural 

 excavations is Howes cave, which has been more fully brought to 



