144 Z. HYDROIDA. Plumularia. 



tween every pair of pinnae. Pinnae alternate, close, parallel, celluli- 

 ferous on the upper side ; the cells separated by a joint and set in a 

 sort of indentation in the stalk. They have been aptly compared by 

 Ellis to the flower of the lily of the valley, being- of a campanulate 

 form with the rim cut into eight equal teeth, while in front there is 

 a stronger spinous process which does not project beyond the cell. 

 The ovarian vesicles are large and remarkably curious : they are pro- 

 duced both from the main stalk and pinnae, are shortly pedicellate, 

 and resemble a swollen pod girded round with from 5 to 9 cristated 

 ribs or bands proceeding from a dorsal tube, and rising- into short 

 spines on the anterior margin. When recent " they are translucent, 

 and six or seven dark oval masses can be seen within each. These 

 seemed to be ova. The vesicle being torn up, and the ova allowed 

 to escape, they were seen to be in form irregularly oval, but contain- 

 ing an opake elongated body in their centre. (Fig. 6, p. 48.) The form 

 of this central body varied in different ova, but it was generally some- 

 what hammer-shaped. Neither the general mass of the ovum, nor 

 this central body were seen to move." Dr Coldstream^ June 10, 

 1833. — Polypes " minute, delicate ; tentacula 10, annulated ; mouth 

 infundibuliform." Dr Coldstream. 



" Each plume," says Mr Lister in reference to a specimen of this 

 species, " might comprise from 400 to 500 polypi ;" and a specimen, 

 of no unusual size, before me has twelve plumes, with certainly not 

 fewer cells on each than the larger number mentioned, thus giving 

 6000 polypes as the tenantry of a single polypidom ! Now many 

 such specimens, all united too by a common fibre, and all the off- 

 shoots of one common parent, are often located on one sea-weed, the 

 site then of a population which nor London nor Pekin can rival ! 

 But PI. cristata is a small species, and there are single specimens of PI. 

 falcata, or Sertularia argentea, of which the family may consist of 

 80,000 or 100,000 individuals. It is such calculations, always un- 

 der-rated, that illusti'ate the " magnalities of Nature," and take us 

 by surprise, leaving us in wonderment at what may be the great ob- 

 jects of this her exuberant production of these " insect-milhons 

 peopling every way." But 



" So He ordain'd, whose way is in the sea, 



His path amidst great waters, and his steps 



Unknown ; — whose judgments are a mighty deep, 



Where plummet of Archangel's intellect 



Could never yet find soundings, but from age 



To age let down, drawn up, then thrown again, 



With lengthened line and added weight, still fails ; 



And still the ciy in Heaven is ' O the depth' !" — Montgomenj. 



