304 REPORT OP COMMISSIONER OF FISH AND FISHERIES. 



The arrangement of the families adopted, and to a certain extent their 

 affinities, are indicated in the subjoined table, in which, however, as 

 throughout the article, special reference is had to the reiiresentatives of 

 the order in New England waters, extralimital species, genera, and even 

 higher groups, Apseudes and the Serolids, for example, being disre- 

 garded. The arrangement will be seen to considerably resemble that 

 of Dr. Fritz Miiller. I have placed the Tanaidce at the other end of the 

 order, partly, however, from the necessity of a lineal arrangement. 



SYNOPTICAL TABLE OF FAMILIES. 



I. Respiration pleonal ; legs not furnislied. with a chelate hand. 

 1. Legs in seven pairs. 



a Antennulse small or rudimentary ; antennae longer, often much elongated. 

 t Uropods terminal, sometimes rudimentary, rami mostly styliform. 

 Legs ambulatory ; autennulae rudimentary ; respiration aerial. 



I. Oniscid^, p. 305 

 Legs x'r^hensile ; sexes very unlike ; adult forms degenerate ; para- 

 sitic II. BOPYRID^, p. 311 



Legs ambulatory or prehensile ; segments of pleon united ; antennae vrith a 



multiarticulate flagellum III. Asellid^, p. 312 



Last three pairs of legs natatory ; segments of pleon united ; antennae with 



a multiarticulate flagellum IV. Munnopsid^, p. 328 



tt Uropods inferior, operculiform. 



Legs prehensile or ambulatory, not ciliated V. Idoteid^, p. 335 



First four pairs of legs ciliated ; last three pairs ambulatory. 



VI. Arcturid^, p. 361 

 6 Antenuulae and antennae subequal ; body not elongated. 



t Uropods lateral, with one ramus obsolete or subrudimentary. 



Antennuloj and antennae well developed; pleon of two segments; uropods 



with one movable ramus VII. SPHiEROMiDiE, p. 367 



Antennulaj and antennae short ; pleon of six segments ; outer ramus of wxo- 



pods small VIII. Limnoriid^, p. 371 



tt Uropods lateral, distinctly biramous; rami mostly lamelliform. 



Mouth caruassial ; legs not aucoral ; antennulae exposed in front ; jileopods 



ciliated IX. CirolaniDvE, p. 376 



Mouth suctorial ; first three pairs of legs ancoral ; antennulae exposed in 



front : X. ^GiD^, p. 382 



Mouth suctorial ; legs all ancoral ; antennulte concealed at base by the pro- 

 jecting front ; pleopods naked XI. Cymothoid^, p. 390 



Antennulte and antennae subequal, or antennulae much the largest in the males ; 

 body cylindrical, elongated, 

 t Uropods lateral and superior. 



Legs ambulatory or prehensile XII. Antiiuridje, p. 396 



3. Legs in the adult in six, ai)parently only five, pairs. 



Five pairs of legs ambulatory ; antennulae and antennae subequal. 



XIII. GnathiidvE, p. 408 



II. Respiration cephalothoracic ; first pair of legs terminated by a chelate hand. 



Lege ambulatory and prehensile ; head united with the first thoracic seg- 

 ment; autennular flagellum single XIV. Tanaidce, p. 413 



m 



