184 Mr Heiiry Good«ir on a JSfew Genu*\ 



and formed into a distinct order, viz. the Lcemodipoda or Lee- 

 mipoda. This order has been further subdivided into two 

 families, viz. the Lcemodipoda FlUformia, and the Lcemodijyoda 

 Ovalia. It is the first or Filiform Lcemodipoda and the genus 

 Caprella of this family which will engage our attention at 

 present. I have had considerable opportunities of examining 

 the animals belonging to this genus in a living state, and by 

 this means have been enabled to draw up a short account of 

 their history. Little is at present known either of their inter- 

 nal structure or habits. This is owing, in a great measure, 

 to two causes ; firstly, to their pelagic habitats, and, secondly, 

 to the peculiar structure of their bodies, which much resembles 

 in its external appearance the coralines which they inhabit, 

 on which account they are apt to be overlooked. In general, 

 too, they are almost colourless, although they are very often 

 found of various colours, carmine, green, brown, and all the 

 intermediate hues. 



The body of the Caprellce^ exclusive of the obsolete abdo- 

 men, is composed of seven segments, bearing five pairs of am- 

 bulatory legs ; the second and third thoracic segments, each 

 bearing one pair of membranous finlets, which act, to a certain 

 extent, as organs of respiration. There are two pairs of an- 

 tenna, and the mechanism of the mouth* is rather complicated. 

 The digestive canal is a simple straight canal, which, during 

 its course through the post occipital and first thoracic seg- 

 ments is considerably dilated ; after this, however, it runs to 

 the distal extremity of the body without farther complication. 

 It is seen to pulsate at irregular intervals, and this is observed 

 at that part only immediately above the ovarian openings ; the 

 ovaries when present, are attached to the digestive canal at 

 this point by cellular structure, and by this means they also 

 are subject to this pulsation. The vascular system in the 

 caprellae is composed of two sets of vessels, the one arterial, 

 the other venous. These are most easily observed in the an- 

 tennae ; the main artery runs along the superior, and the vein 

 along the inferior edge of the antenna ; lesser branches either 

 spring from or run into these main trunks. A large dorsal 

 vessel is seen in the trunk ; but owing to the greater opacity 



* M. Edward's Hist, des Crust., vol. iii. p. 103. 



