— 3 o — 



Pin a larva to the cork or beeswax lining of a dissecting 

 dish, with its ventral aspect uppermost, and cover it with 

 water. Make a drawing of the ventral surface. Name the 

 regions and the appendages of the body shown in this view. 

 The long, tapering appendages on the margins of the abdo- 

 men may be termed the lateral filaments ; the tufts of hair- 

 like appendages near the bases of the lateral filaments are 

 tracheal gills ; and caudad of the ninth abdominal segment 

 is a pair of prolegs. Thess may be termed, the anal pro- 

 legs* 



Make a drawing of each of the following parts : — 

 i. The dorsal aspect of the head, showing the mandibles, 

 the antennae, and the labrum. 



2. The ventral aspect of the head, showing the labium and 

 the maxillae. 



3. The lateral aspect of the head, showing the number and 

 position of the eyes. 



4. One of the true legs ; name the parts of the leg. 



5. The anal prolegs. 



6. One of the tufts of tracheal gills. First remove the 

 tuft with a pair of small scissors. Cut close to the ventral 

 surface of the body, so that the entire tuft will remain to- 

 gether. Examine the tuft with a lense or with a compound 

 microscope using a low power. The tuft is separated into 

 two parts by a deep fissure. The mesal part is the larger, 

 and is again divided into two parts. Each of these three 

 primary divisions is composed of several bundles of tracheal 

 gills. These are each composed of from two to twelve hair- 

 like branches. 



7. One of the tracheal gills. Cut off several of the hair- 

 like branches and mount them in glycerine, using a thin 



*Many larvae bear upon the abdomen locomotive appendages, which resemble 

 legs, and are termed prolegs. This is especially true of caterpillars, which bear 

 from one to five pairs of these appendages. The prolegs are temporary organs, 

 being shed with the skin when the larva transforms to a pupa. 



