Miscellaneous. 327 



gated, organized, and gradually converted into a true Echinorhynchus. 

 The latter is therefore formed within the primitive embryo like an 

 Echinoderm in its Pluteus, or a Nemertes in its Pilidium. It 

 rapidly increases in size, becoming tvi^ice or three times its former 

 length, and finally fills the body of the embryo completely. The 

 latter is not destroyed, but persists and becomes transformed to con- 

 stitute the envelopes external to the muscular tube of the worm — 

 envelopes which are distinguished, as has long been known, by the 

 existence of a proper vascular system. The primitive cuticle and 

 the bundles of spines disappear ; but this slight moulting is a phe- 

 nomenon of far less importance than the casting of the Pilidium by 

 the young Nemertes. 



When the cephalic armature of the Echinorhynchus is formed, it 

 draws back into the posterior part of its body like a Cysticercus in 

 its vesicle. 



The number of these parasites is sometimes very considerable. 

 Prof. Leuckart has counted as many as fifty or sixty in a single 

 Gammarus) but in this case they often destroy their host. — Nach- 

 richten der hon. Ges. der Wiss. zu Gottingen, Oct. 1862 ; Bibl. 

 Univ. March 20, 1863, Bull. Scient. p. 245. 



Note on the Animal of Lithotis rupicola. 

 By William T. Blanford, A.R.S.M., F.G.S. 



Since sending the descriptions of Lithotis and Cremnobates (see 

 p. 184) I have obtained much finer specimens of the former shell 

 from the same locality — the rocks of the Bhore Ghat. The animals 

 being in full vigour, I had a better opportunity of observing them : 

 those previously captured were aestivating and very sluggish. One 

 or two of the characters previously noted require correction, and I 

 have observed some additional particulars of interest. 



The foot, during the monsoon, is rather longer than the shell, and 

 oval, the head-lobe being separated by a groove. There is no trace 

 of the lower pair of (true) tentacles ; the upper pair, or eye-pedicels, 

 are much swollen and mammiform towards the base. The upper jaw 

 is horny and arcuate ; the lower lip deeply cleft. Mantle closed, 

 with the exception of a circular orifice at the end of the siphonal 

 ridge in the shell. 



The largest specimen I now possess measures 1 0| millimetres by 7, 

 and is 3| mill. high. 



Lithotis abounded upon the surface of the damp rocks. Cremno- 

 bates occurred only where water ran down the face of the cliff, thus 

 confirming my expectation of the latter proving to be an amphibious 

 rather than a terrestrial form. 



Poona, Aug. 6, 1863. 



Habits of the King-Crab (Polyphemus). 

 By Dr. J. E. Gray, F.R.S. &c. 



Several uses have been suggested for the elongated spine-like tail of 

 this genus of Crustacea. They have several specimens alive in a 

 shallow tank in the Liverpool Museum ; and Mr. Moore showed me 



