90 MEMOIES OF THE NATIONAL ACADEMY OF SCIENCES. 



NORTH AMERICA— Continued. EUROPE— Continued. 



HYMENOPTEEA. 



| Typhlopone clamii Joseph. Carniola. 



VERTEBEATA. 



PISCES. 



Amblyopsis spelceus DeKay. Mammoth, Wyan- 

 dotte, and Emerson's Spring Cave, in a pool 

 communicating with [Green?] river. J. E. 

 Proctor. Caves and wells in Indiana and 

 Kentucky. 

 Chologaster cornutus Agassiz. Subterranean 

 streams in Mammoth Cave and 

 in Tennessee. 

 agassizii Putnam. 

 Chologaster papilliferus Forbes. Subterranean 



streams and wells in Illinois. 

 TyphlicMhys subterraneus Girard. Subterranean 

 streams of Kentucky, Tennessee, and Alabama. 



BATEACHIA. 



I Proteus anguineus Laur. Subterranean waters of caves 

 I in Carniola and Dalmatia. 



VII.— LIST OF N0N-CAVERNIC0L0US BLIND OR EYELESS ANIMALS. 



It may be regarded as a matter of some interest to obtain a rough idea of the number of blind 

 or eyeless Arthropoda and Yertebrata, which do not live in caves, for comparison with the list of 

 cave animals. It will be seen that the lists are nearly of the same extent. 



It will also be seen how very small a proportion the blind, non-cavernicolous animals of the 

 two higher branches of the animal kingdom bear to those of normal vision. There are known to 

 be not less than from one to two hundred and fifty thousand species of Arthropods and mammals, 

 while the blind forms amount to a very small percentage of this number. 



Before beginning our list we may glance at the groups of lower invertebrates which are eye- 

 less, being either primitively without any organs of vision, or which belong to groups where all 

 the species have become adapted to a stationary or parasitic (internal or external) mode of life. 



Protozoa. Without exception eyeless, though some forms have sensitive " eye-spots." 



Porifera. Without exception eyeless. 



Calenterata. Many, perhaps a large proportion, eyeless. 



Echinodermata. All, except Asteroidea, eyeless. 



Pohjzoa. All, without any known exception, eyeless. 



Brachiopoda. Adult forms eyeless, the larv;e of some having temporary eyes. 



Vermes. Cestoids, Trematoda, and nearly all the other parasitic forms, with Lumbricus, etc., eyeless. 



Hollusca. All fresh-water Lainellibranehiata, and many marine forms, without eyes.* 



* In regard to eyeless Mollusca I applied to Mr. W. H. Dall, who was kind enough to supply me with the follow- 

 ing information : 



"To fully answer your letter would take nearly a book of itself. But in a few words I will try to give you an 

 answer, such as it is. I do not know of any eyeless Cephalopods. Among the Lamellibranchs the vast majority have 

 no eyes; developed eyes are very exceptional, but sense organs sensible to light (but not exactly eyes) have been 

 found in several species and may exist iu many more. We know the characters of the soft parts in only about one 

 species in five thousand, so that it is impossible to generalize with safety. Among Gastropods the majority have 

 eyes. The presence or absence of eyes is not of much importance in classification, but their position when present 

 is important. One species of a genus may be blind and another have eyes. Among littoral species those which 

 burrow in the sand, like Natica, Sigaretus, Bullia, Scaphander, Philine, etc., are very apt to be blind, but others of 

 the same habit are not. The Chitonidse are all blind if we look for the eyes in the usual place ; but in certain groups 

 there is the wonderful apparatus for seeing through the shell, described by Moseley. Nearly all the Pteropods and 

 Janthina are blind. Most of the Heteropods, though leading a similar life, have well-developed, movable eyes. 



