LUMBRICUS. 137 
covered by the sea, this creature is extremely impatient of light ; and in 
confinement it continually attempts to penetrate downwards, even when 
there is no sand in its vessel. But if amply provided with this material, 
it soon screens itself from view, and in burrowing, the head, enlarged, 
as shewn by fig. 2, seems to be employed in effecting its descent. 
These animals form a thin coating of sand, which is of some tenacity, 
investing the body just like a piece of thin linen wrapped around it. 
When a specimen is removed from its residence, it seems to attempt 
divesting itself of this covering, and to experience difficulty in doing so. 
The distinctive character of the species consists in the branchia, oc- 
cupying only an intermediate portion of the body ; the posterior, there- 
fore, bearing none, is of different formation. 
2. Another species of the Lumbricus marinus, which I have not 
hitherto observed to be described, though it is unlikely to have been 
overlooked, inhabits our seas. 
This is somewhat smaller than the former, the body consisting of 
numerous setiferous and branchiferous annulations. 
The branchiz commence, as in the other, at some distance from the 
anterior extremity, but they continue, without interruption, down to the 
posterior extremity, or its immediate vicinity, bemg about thirty-eight 
pair in all. They occupy every segment from their commencement, 
except the last. The lower extremity termimates in a knob. The 
branchize are dichotomous, originating from a root, and successively sub- 
dividing into several members. They are somewhat incurved, and some 
of them have a faint reddish appearance towards the root, but of this 
portion it is not easy to obtain a view. Their action much resembles 
that of the branchiz of the Terebella. 
The setiferous papilla are prominent, running down from the ante- 
rior to the extremity. There are about fifteen pair of pencils between 
the anterior and the commencement of the branchiz. The pencils are 
composed of several bristles. 
Colour of the whole animal very dark green.—Plate XIX., fig. 4 ; 
head when globular, fiz. 5 ; branchiz, fig. 6 ; substances like ova, fig. 7. 
Ss 
