GENERAL BIOLOGY 



b. A groove, the cervical suture runs across the carapace and 

 marks off the head from the thorax. 



c. On the ventral side, the region between the appendages is 

 very narrow; the anterior appendages project forward and not 

 downward as do the more posterior ones. 



d. The locomotor appendages are attached to the thorax ; the 

 posterior pair are upon a movable somite while all the others arise 

 from a fused single mass continuous with the head. 



e. The free lateral part of the carapace, above the appendages, 

 is the branchiostegite. Raise its edge and see that it covers the gills. 



f . Respiratory organs : Remove one of the branchiostegites, 

 study the gills under water and observe: Six of them are attached 

 to the appendages, podobranchiae ; eleven of them are attached to 

 the soft cuticle joining the appendages to the body arthrobranchiae. 

 At the anterior end of the branchial cavity a canal leads forward 

 toward the mouth and in this lies the flat part of the second maxilla 

 called the scaphognathite. 



D. APPENDAGES. 



Starting at the posterior end carefully remove all of the ap- 

 pendages from one side with all the basal parts of each, see which 

 are alike and then draw one of each kind or set (15 figures for the 

 female, 15 for the male) keeping all of the small ones in water in 

 watch glasses. 



I. ABDOMINAL APPENDAGES OR SWIMMERETS. 



Composed of a two jointed protopodite, and an exopodite and 

 endopodite each with many joints ; found on all but the first and 

 sixth somites (and the second also in the male) where the appen- 

 dages are more or less modified. 



II. THORACIC APPENDAGES. 



There are five pairs of ambulatory, and three pairs of mastica- 

 tory appendages (the maxillipedes.) 



a. The posterior pairs of ambulatory appendages have the fol- 

 lowing seven joints: (i) Coxopodite, the short and very thick 

 basal joint. (2) Basipodite, a very small and conical joint. (3) 

 Ischiopodite, cylindrical and with a groove around it. (4) Mero- 

 podite, very much longer than the last. (5) Carpopodite, about 

 half as long as the last. (6) Propodite, slender and long. (7) 

 Dactylopodite, the short, pointed terminal piece. Of these (i) and 



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