MARLNIB GAMMARIDEAN AMPHIPODA 509 



mandibles as the two mouthparts often are closely connected mth 

 tissues and the mandibles will tear the lower lip when being removed. 



The upper lip and epistome are not removed from the head at 

 this time. Their interrelationship from lateral view must be pre- 

 served. The observer should note the condition of the ventral margin 

 of the upper Up from anterior view (rounded, incised, truncated) 

 before mounting the carcass on the depression sHde. 



Mouthparts are transferred to a tiny drop of glycerine on a flat 

 slide, arranged in sequence and fitted with a cover slip. Preferably 

 the mouthparts are arranged so that the following parts project 

 upward or are on top: mandibular molars and the inner lobes of 

 lower Hp, maxillae, and maxilUpeds. If the base of the maxillipeds 

 curves upward, it may be cut off so that the cover slip will set firmly. 

 The mandibles should be arranged with the molars projecting 

 obliquely toward the observer or directly lateral, if the center of 

 gravity so permits. Often mandibles are placed on a separate slide 

 with supports for the cover shp to prevent crushing. Supports may 

 be made of wire or sand grains. 



Because a unilateral dissection has been made, the remaining 

 amphipod carcass has a complete set of pereonal and pleonal parts 

 remaining on one side (the left if done by a right-handed operator). 

 Coxa 1 and any other (left) legs are removed which would obscure 

 the head and pleon from lateral view. The carcass is mounted right 

 side down in the glycerine of the depression slide and a cover shp 

 firmly set. If the amphipod is so large that it wall be crushed by 

 the cover shp or lie in a tilted position, two pieces of wire of appro- 

 priate thickness (or variously thick insect needles, pins, paper cHps 

 cut with nipping pliers) are placed on each side of the amphipod, 

 which is covered with sufficient glycerine to fill the area between 

 the two wires, and the cover slip set on the supports. The top glass 

 should fit the carcass snugly so as to hold it in place but not to crush 

 it. Glycerine has sufficient surface tension so that it will not leak 

 out from under the elevated coversHp as long as the sUde is kept 

 in a horizontal position. 



One now returns to the first flat sHde on which were placed the 

 seven right pereopods (including gnathopods) and the two right 

 antennae. They are arranged in order from anterior to posterior in 

 two rows. Gills from legs 2 to 7 (or 2-6 or 2-5) are removed and 

 placed in sequence on the fourth flat sUde of glycerine. If the animal 

 is a female, the brood lamellae are removed in sequence and placed 

 in a row on another slide. At this stage one is working from glycerine 

 to glycerine without the effects of a change in surface tension so 

 that it is easy to keep the parts in order, making notes of charac- 

 teristics that will permit proper orientation. Cover shps are set 

 in place. 



