478 THE TIMBER-BORING SHRIMP, OR 6RIBBLE. 



Several of these species take possession of the corallines, each selecting a particular branch, 

 and not permitting any other to intrude upon its premises, lighting with great valor against 

 any assailant. 



They resemble the fly-catchers in some of their habits, sitting patiently on their branch 

 until they see some little creature passing within reach. They then dart at their prey, seize 

 it, return with it to their resting-place and there eat it leisurely. They sit in a curious erect 

 attitude, swaying the body about and occasionally cleaning the antennae by drawing them 

 through the tufted feet. 



The common Fish-louse is parasitic upon many species of fish, clinging tightly by means 

 of their hooked legs. It is thought by many fishermen that the creature is by no means hurtful 

 to the fish, but that it is absolutely beneficial, causing death if removed. 



A rather curious and tolerably plentiful species of Isopod crustacean is the Shrimp-fixer, 

 so called from its habit of affixing itself to shrimps and prawns, concealing itself under the 

 side of the carapace. Any number of these curious parasites may be obtained from a fish- 

 monger's shop, by the simple process of looking over his stock of prawns, and picking out 

 those which have a swelling at the side of the carapace. The fishermen, who have the 

 oddest ideas about marine objects, and know as little about shrimps as a ploughman about 

 worms, generally fancy that these parasites are young soles! probably on account of the gen- 

 eral shape of the male. 



The female of this crustacean is generally found with a mass (if eggs which are congregated 

 beneath the body, and are kept in their places by the pouch formed by the prates attached to 

 the legs. Owing to the pressure caused by the carapace of the prawn, the sides of the Shrimp- 

 fixer are dissimilar, and distorted individuals are very common. 



In all the members of this genus the male is much smaller than the female, being barely 

 one-sixth the size of his mate, and is narrow and elongated, whereas she is wide, pear-shaped, 

 and ending in a point. The false legs are ten in number, live on each side, and modified into 

 triangular membranous plates, forming a pouch for tin' reception of the eggs. 



The color of this species is greenish, with a slight lustre above, and dark at the edges of 

 the plates. 



The members of the genus lone may fie known by the appendages of the abdomen, which 

 are thread-like and arranged round the body. The female is also larger than the male. 



This creature is also a parasite like the preceding, but makes its home within the thoracic 

 plate of the burrowing crab {Callianassa subterranea), which has already been described on 

 page 464. It forms a tumor on the side, and can be removed in a living state. It seems that 

 both sexes are to be found under the same shell, the tiny male holding firmly to the appen- 

 dages of his mate like a little child holding to its mother's dress. The color of this species is 

 orange-yellow, and the appendages are white. 



Mr. Tuffen West has favored me with the following remarks upon an allied crustacean: — 

 "Some years ago, I assisted in the dissection and made drawings of the male and female of a 

 remarkable crustacean taken from the gills of a hermit-crab. It was thought that a new genus 

 would have to be constituted for it. In the female of this species there was a distinct space 

 left between the plates covering the ova, for the accommodation of the male, and it is thought 

 doubtful whether he ever takes any food. The males are model husbands ; having once selected 

 a mate, they never leave her. 11 



Another wood-boring crustacean is called the Timber-boring Shrimp, or Gribble. 



Though belonging to another family, this creature is as destructive as that which has 

 already been described, but makes its tunnels in a different manner, burrowing deeply into 

 the wood instead of driving oblique passages. It proceeds in a very methodical manner, 

 the tunnels being quite straight unless they happen to meet a knot, when they pass round 

 the obstacle and resume their former direction. Small as is this crustacean, hardly larger, 

 indeed, than a grain of rice, it is a sad pest wherever submarine timber is employed, for it 

 works with great energy, and its vast numbers quite compensate for the small size of each 

 individual. It appears to attack equally any kind of wood, though its progress is slower in 



