rilYIAM AUTIIh'orohA 101 



The /////■(/ tiHi.rilli/Kd is one of I lie most coiiiijIcIc of ihrsi' 

 :il)IH'ii(l;i^('S and will he used as an approach to the study (»f the 

 whole series. Compare with a swimmeret. Identify the parts, 

 note differences, and determine the type. Express the results 

 in writing and submit as a part of the laboratory report. These 

 comparisons may be expressed in the form of a tal)le. 



The second maxilliped possesses essentially the same com- 

 ponents as the third, l)Ut the exopod is relatively larger, the 

 cndopod smaller. 



In the first maxilliped the coxopod and the basipod are broad, 

 thin plates, while the cndopod is short and only two-jointed. 

 The undivided portion of the exopod is very long. In place of 

 the podobranchia is a broad membranous plate. 



Examine the left third ic(dking leg and compare with the third 

 maxilliped. This walking leg has a coxopod with an epipod and 

 a gill, a basipod and an endopod of five joints. The exopod is 

 lacking, and therefore this more specialized unforked type is 

 known as a uniramous appendage. Note the pinccr formed l)y 

 the prolongation of one angle of the distal end of the penultimate 

 joint, thus forming a fixed jaw for the last joint to work against. 

 Examine the other walking legs. Do all have pincers, epipods, 

 and gills? The first pair is greatly enlarged, with a powerful 

 pinccr for offensive and defensive use. 



Draw the left third maxilliped and left third walking leg in the 

 same relative positions. 



The Appendages of the Head.— Remove the remaining 

 appendages of the left side and arrange in a series for study and 

 comparison. 



The coxopod and basipod of the second maxilla are still thinner 

 and more lamellate than is the case of these parts in the first 

 maxilliped and are subdivided by deep fissures which extend 

 from their inner edges. The endopod is very small and undivided, 

 while the .so-called bailer is probably formed by a fusion of the 

 exopod with the epipod. The bailer moves in such a manner as 

 to draw water through the branchial chamber over the gills 

 from the caudal end. 



In the first maxilla the exopod and epipod have disappeared, 

 and the endopod is insignificant and unjointed. Its two inner 

 thin plates are the protopod. The small process in front of this 

 appendage in the head is not considered as an appendage i)Ut as 

 a part of the lower lip. 



