182 On the Crustacea of the 'Albatross ' Dredgings in 1883. 



1000 fathoms. Below this depth orange-red of varying m- 

 tensity is apparently the most common colour, although in 

 several species, very notably in the Notostomus already 

 referred to, the colour was an exceedingly intense dark 

 crimson. 



The eyes of these abyssal species are even more remarkable 

 than their colours, as the following list of the Decapoda and 

 larger Schizopoda taken below 2000 fathoms by the ' Alba- 

 tross,' with the notes which follow, will show : — 



fathoms. 



1. ParapasTirus pilosimauus 1731 to 2221 



2. Pontopliilns abyssi 1917 to 2221 



3. Nematocarciiius ensiferus 588 to 2030 



4. Acautliephyra Agassizii 105 to 2S_)-19 



5. Acautliephyra, sp 2929 



6. Genus allied to Acautliephyra .... 1395 to 2929 



7. Hymeuodora ylacialis 888 to 2030 



8. Parapasipliae sulcatifrous 616 to 2929 



9. Parapasiphae compta 2369 



10. Amalopeuseus elegans 640 to 2369 



11. Aristeus ? tridens 843 to 2221 



12. tlepomadus teuer 2949 



13. Sergestes mollis 373 to 2949 



' 14. Gnathophausa, sp 858 to 2033 



15. Guathophausa, sp 959 to 2949 



16. Lophogaster, sp 1022 to 2949 



In every one of these sixteen species the eyes are present, 

 in the normal position, and distinctly faceted. In nos. 3, 4, 

 5, 6, 11, and 12 the eyes are well developed, black, and, 

 while somewhat smaller than in the average Palsemonidee 

 and Penseidffi, not conspicuously smaller than in many 

 allied shallow-water forms. In 1 the eyes are black, but con- 

 spicuously smaller than in the allied shallow-water species. 

 In 13 the eyes are black and of moderate size. In 9 they 

 are apparently black or nearly black and small. In 2 

 they are nearly colourless in alcoholic specimens and rather 

 larger than usual in the genus, but considerably smaller than 

 in Pontophilus gracilis^ a very closely allied species found in 

 200 to 500 fathoms. In 7 and 8 they are small and light 

 coloured. In 10 they are rather small and dark brown. In 

 14, 15, and 16 they are not conspicuously different in size 

 from those of allied shallow-water species and are dark 

 brown. 



However strong may be the arguments of the physicists 

 against the possibility of light penetrating the depths from 

 which these animals come, the colour and the structure of their 

 eyes, as compared witli those of blind cave-dwelling species, 

 show conclusively that the darkness beneath 2000 fathoms of 



