MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 91 



Class PYCNOGONIDA. 



The deep-sea species are either eyeless or with rudimentary eyes. 



Class CEUSTACEA. 

 Order Cirripedia. 



Rhizocephala. All are eyeless, while the harnacles have rudimentary eyes. 



Order Branchiopoda. 



Bradya Kmicola Herrick. In mud in ditches, near Mobile, Ala. 

 Bathynella natans Vejovsky. Eyeless. Wells in Prague. 



Canthocamptus cryptorum Brady. " Eyes wanting ; " (?) none represented in the figure. In a coal mine, New- 

 castle, England. 

 Siphonosiomata. All the members of this group of ectoparasites are eyeless. 

 Cypris eremita Vej. White and eyeless. Wells in Prague. 



For preparing the following list of higher Crustacea, mostly deep-sea forms, I am indebted to 

 Prof. S. I. Smith, of Yale University. 



Order Amphipoda. 



Anonyx calcaratus G. O. Sars. "No distinct eyes." North Atlantic, 600 to 1,200 fathoms. 



A. typhlops G. O. Sars. "No eyes." North Atlantic, 1,700 fathoms. 



Tryphosa pusilla G. O. Sars. "No eyes." North Atlantic, 1,000 fathoms. 



Acidostoma laticorne G. O. Sars. "No eyes." North Atlantic, 200 fathoms. 



Harpinia abyssi G. O. Sars. "No eyes." North Atlantic, 350 to 2,200 fathoms. 



H. carinata G. O. Sars. "No eyes." North Atlantic, 600 to 778 fathoms. 



H. mucronata G. O. Sars. " No eyes." North Atlantic, 150 to 600 fathoms. 



H. serrata G. O. Sars. "No eyes." North Atlantic, 100 fathoms. 



Urothor abbreviata G. O. Sars. "No eyes." North Atlantic, 600 fathoms. 



CEdiceros macrocheir G. O. Sars. " No eyes." North Atlantic, 1,000 fathoms. 



Mcera tenera G. O. Sars. "No eyes." North Atlantic, 417 fathoms. 



Melita pallida G. O. Sars. "No eyes." North Atlantic, 1,300 fathoms. 



Biuzelia serrata G. O. Sars. "No eyes." North Atlantic, 350 fathoms. 



Danaia abyssicola G. O. Sars. "No eyes." North Atlantic, 447 fathoms. 



Lilljeborgia cequicornis G. O. Sars. " No distinct eyes." North Atlantic, 95 to 147 fathoms. 



Ampelisca odontoplax G. O. Sars. "No eyes." North Atlantic, 142 fathoms. 



A. minuticornis G. O. Sars. "No percepiible eyes." North Atlantic, 350 to 634 fathoms. 



Byblis abyssi G. O. Sars. "No eyes." North Atlantic, 350 to 620 fathoms. 



Podocerus brevicornis G. O. Sars. " No eyes." North Atlantic, 146 to 767 fathoms. 



P. tenuieornis G. O. Sars. "Eyes wanting." North Atlantic, 1,110 fathoms. 



Unciola petalocera G. O. Sars. "No eyes." North Atlantic, 350" to 650 fathoms. 



Dulichia macera G. O. Sars. " Eyes rudimentary." North Atlantic, 450 to 870 fathoms. 



Hyperiopsis voringii G. O. Sars. Eyes rudimentary. North Atlantic, 1,280 fathoms. 



Stegocephalus gibbosus G. O. Sars. "No eyes." North Atlantic, 120 fathoms. 



S. auratus G. O. Sars. "No distinct eyes." North Atlantic, 100 fathoms. 



Archibenthal and abyssal mollusks are often blind, as of course you are well aware, but many are not. I have not found 

 any with exceptionally well-developed eyes. The Strorabs, which live in shallow water, and some of the Cephalopods 

 have eyes comparable to those of vertebrates. Many embryo mollusks have eyes which they lose ou becoming adult. 

 Cave land shells are frequently blind. The Zonites subrupivola I described from your Utah cave was blind; and, by 

 the way, I have the same species from above ground, under stones in California, since, but not with the soft parts. 

 The big Auriculas (A. judex, for example) are blind. They live under dead leaves in forests. Several bliud species of 

 Zospeum and a i?eZu:(Amuionitella) hauffeni are found in the grottoes of Carniola. Ou the other hand, the Onchidium 

 of the tropics has, like some Chitons, eyes in its back, described by Semper, besides its normal tentacular eyes, while 

 the very similar uortheru Onchidella has only the latter. Ca;cilianella and Geostilbia are French cave land shells 

 without eyes. The Sepia has lids to its eyes and is the only mollusk which can tip you a wink !" 



Although living snails were fouud in nearly all the caves examined and collections of them made, which are 

 mostly in the Museum of Comparative Zoology at Cambridge, they have not been carefully examined and identified. 

 None are known to be peculiar to caves, and the shells are of the normal color, not bleached. It is, however, of 

 interest to observe that Dc Rougemont in his essay on Hydrobia found in the wells of Munich and in Falkeusteiu 

 Cave this species, not found in the upper world. He states that the existence of eys in this species is not positively 

 proved, although Wiedersheim, who first found this snail in the Falkenstein Cave, speaks of the existence of visual 

 organs on the tentacles. De Rougemont adds that in the Hydrobia from Munich he has seen no such traces : "Les 

 tentacules e'taient d'une uuiformite' complete de leur base a leur extr6mit<5" (Etude, etc., p. 45). Good transverse 

 microscopic sections would probably readily enable one to settle the point whether traces of eyes exist in this interest- 

 ing mollusk. 



