304 REPORT OF 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, a,s 

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

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

 higher groups, Apscudes 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 furnished with a clielate hand. 



1. Legs in seven pairs. 



a AntennulfB small or rudimentary ; antennae longer, often much elongated, 

 t Uropods terminal, sometimes rudimentary, rami mostly styliform. 

 Legs ambulatory ; antennulas rudimentary ; respiration aerial. 



I. OXISCIDJE, p. 305 



Legs prehensile ; sexes very unlike ; adult forms degenerate ; para- 

 sitic II. BopYnrrxE, p. 311 



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



multiarticulate flagellum III. ASELLHXE, p. 312 



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



a multiarticulate flagellum IV. MUNNOPSID^E, p. 328 



tt Uropods inferior, operculiform. 



Legs prehensile or ambulatory, not ciliated V. IDOTEIIXE, p. 335 



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



VI. ARCTURID^E, p. 361 

 6 Antennulae and antennae subequal ; body not elongated. 



t Uropods lateral, with one ramus obsolete or subrudimentary. 



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



with one movable ramus VII. SPH^EROMID^E, p. 367 



Antennulas and antennas short ; pleon of six segments ; outer ramus of nro- 



pods small VIII. LIMNORIID^E, p. 371 



tt Uropods lateral, distinctly biramous; rami mostly lauielliform. 



Mouth caruassial ; legs not ancoral ; autennuloe exposed in front ; pleopods 



ciliated IX. CIROLANHXE, p. 376 



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



front X. JEGiDJE, p. 382 



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

 jecting front ; pleopods naked XL CYMOTHOHXE, p. 390 



cAntenuuLe and antennas subequal, or antennulas much the largest in the males; 



body cylindrical, elongated, 

 t Uropods lateral and superior. 



Legs ambulatory or prehensile XII. ANTHURID^E, p. 396 



2. Legs in the adult in six, apparently only five, pairs. 



Five pairs of legs ambulatory ; anteunulas and antennas subequal. 



XIII. GXATHIIDJE, p. 408 



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



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

 ment ; antenuular flagellum single XIV. TANAID^E, p. 413 



