Suborder 1. 



Myodocopa. 



General Characters. Shell exhibiting in front a persistent aperture, as ; 

 rule widened by a more or less deep insicure of each valve in this place, and allow 

 ing the antennas to be extruded and freely moved. A frontal tentacle always present 

 Anterior antennae never natatory, and more or less dissimilar in the two sexes 

 Posterior antennae constituting the sole locomotory organs of the animal, thei 

 basal part being remarkably large and muscular, outer ramus very movable 

 multiarticulate, and provided with strong natatory setae; inner ramus neve 

 natatory, being more or less rudimentary, and in male generally transforme< 

 to a grasping organ. Mandibular palps strongly developed, sub-pediform 

 geniculate on the middle, and clawed at the tip. 4 pairs of postoral limb 

 present, exhibiting a very varying structure. Caudal rami lamelliform, edgec 

 behind with strong claws. A well developed heart present in the middle o 

 the dorsal face. Intestine simple without any coecal appendages. Testicle 

 likewise of a very simple structure. 



Remarks. The most prominent feature distinguishing this suborder i: 

 unquestionably the restriction of the locomotory faculty to the posteririor an 

 tennae, the outer rami of which are in reality the only parts by which the bod\ 

 is propelled. For this purpose of course a very powerful muscular apparatu: 

 is needed, and these muscles are found lodged within the basal part of th< 

 antennae, the remarkable size and massive shape of this part being thereby 

 easily explained. During motion the said rami are extended from the fronta 

 opening of the shell and inserted at the base within the incisures of the valves 

 working like a pairs of oars by powerful strokes outwards and behind, thu: 

 propelling the animal. 



The Myodocopa comprise 2 very sharply defined families, the Cypridinida 

 and the Conchoeciidce, which by some authors have been regarded even a: 

 groups of a higher systematic rank (see above). Both these families are wel 

 represented in the Fauna of Norway. All the known forms are exclusively marine 



