2Y4 S. 1. Smith — Amphipodns genera., 



at the distal end of each of the other segments of the peduncle. The 

 proximal segments of the antenna are also dark-colored, and there is 

 a broad band of color at the distal end of the fourth segment. Other 

 parts of the pedimcles of the antennulse and antennae are semi-translu- 

 cent, and so are the flagella. The head and the whole anterior and 

 middle portions of the body of the animal and the epimera are more 

 or less colored in the same way, as are the gnathopods and the bases 

 of the first and second peraeopods ; but the distal portions of these 

 peraeopods, the whole of the third, fourth and fifth pairs, and the cau- 

 dal appendages are semi-translucent and nearly or quite devoid of 

 pigment. 



Two adult specimens give the following measurements : 



Male. Female. 



Length from front of head to tip of telson, 4-2mm 4-4mm 



Length from front of head to second segment of 



pleon in natural position of rest, 3 '5 3 6 



Length of attennnla, 2-4 1-7 



Length of tube, 5-4 5-5 



Diameter of tube at middle, -80 -85 



In the largest specimens seen the tubes are about "7""" long and 

 Q.ginni jj^ diameter, while in the smallest they are only 2"'™ long and 

 0-45™'" in diameter. 



The tubes of all the specimens seen are black externally, thin, and 

 very regularly cylindrical, excejit that they are usually slightly en- 

 larged at one or at both ends. Within they are smoothly lined with 

 a layer of cement, while externally they are covered, to a great 

 extent at least, with minute, elongated pellets, apparently the excre- 

 ment of the animal,* arranged transversely to the tube and closely 



* In several allied species of Amphipoda, the excrement enters largely into the 

 composition of the tube. In 1874 I watched carefully the process of constructing the 

 tubes in several species of Amphipoda. Microdeutopus grandimanus (if. minax 

 Smith) was a particularly favoral)le subject for observation. When captured and 

 placed in a small zoophyte trough with small, branching alga;, the individuals almost 

 always proceeded at once to construct a tube, and could very readily be observed 

 under the microscope. A few slender branches of the alga were pulled toward each 

 other by means of the antennae and gnathopods, and fastened by threads of cement 

 spun from branch to branch by the first and second pairs of perseopods. The branches 

 were not usually at once brought near enough together to serve as the frame-work of 

 the tube, but were gradually brouglit together by pulling them in and fastening them 

 a little at a time, until they Were brought into the proper position, where they were 

 firmly held by means of a thick net-work of fine threads of cement spun from branch 

 to branch. After the tube had assumed very nearly its completed form, it was still 

 usually nothing but a transparent net-work of cement threads woven among the 



