Q PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxvii. 



Pleurogonium, Sars, Leptaspidia Bate and West wood, Nannoniscns 

 Sars, bendrotion Sars, Ischnosoma Sars, Sj)hxro)iudts Dollfus, Stena- 

 sellus Dollfus, Csecosphseroma Dollfus, Hypslmetopus Sayce, Mesota- 

 nais Dollfus, Heterias (new name for Janirella Sayce, preoccupied «), 

 and Phreatoicoide,^ Sayce. 



In a number of species belong-in^ to well-known genera eyes are 

 also lacking. The list includes: Trichoniscus cavernicola Budde-Lund, 

 Astacilla cseca Benedict, Rocinela typJdojjs Bonnier, Munella danteci 

 Bonnier, Brachenridgia camrnarum, Ulrich, Trichoniscus dygius 

 Nemec, Cirolana cuhensis Hay, MonoUstris caeca Gersteecker, Asellus 

 cavaticus Schioedte, Pseiidarmadillo carinidatus Saussure, Conilera 

 stygia Packard, Phreatoicus typicm Chilton, Ilarpxmyx pranizoides 

 Sars, and Serolis anartica Beddard. None of the Munnopsid* or 

 Desmosomidte have eyes. Eyes are likewise usually absent among the 

 Epicaridea. 



Stebbing says that the explanation for the fact that many of the 

 genera of Tanaidaj are blind is to be found in their habit of living 

 ensconced in the sand. 



Many of the blind forms are deep-sea species, others are cave- 

 dwellers, and some have been found in wells at great depths. 



Structural degeneration of the eyes is found in some of the deep-sea 

 Serolida?, no retinula being present, although the vitreous body is 

 represented (Beddard). 



^. Antennse. — There are two pairs of antennss. The first pair are 

 sometimes called antennules, superior or upper antennse. These are 

 rudimentary in the Oniscoidea, are inconspicuous, never more than 

 three-jointed, and sometimes wholly wanting (Helleriidte). Usually 

 the antennules are composed of three peduncular joints and a many- 

 jointed flagellum. The Valvifera, however, are without this nuilti- 

 articulate flagellum, all the joints being consolidated to form a single 

 clavate joint. The flagellum of the flrst pair of antennae in the Tanaidre 

 is rudimentary or sometimes wanting in the female. This is also true 

 of Cyathura Stebbing, females, Lep^tanthura Sars, females, Janthopsis 

 Beddard, Jseropus Koehler, Macrostylis Sars, and Hannoniscus Sars, 

 all having a rudimentary flagellum to the antennules. In the genera 

 Anuropus Beddard and Wannoniscus Sars, the first antenna have but 

 two joints. In Plakartliriwn^ Chilton, the antennules have but three 

 joints, the first two of which are flattened and form plates surrounding 

 the anterior margin of the head. The Apseudida^ are characterized by 

 having two multi-articulate flagelli to the superior antennae, the second 

 flagellum being sometimes called the secondary filament. 



The second pair of antennae, inferior or lower antenna, are usuall}' 

 composed of five peduncular joints and a multi-articulate flagellum. 



a Janirella Bonnier, a new genus of ^l.W//<f,T is described, Ann. Univ. Lyon, XXVI, 

 1896. 



& Chelonidiurii Pfeffer is a synonym of I'ldkarUir'nnn Chilton. 



