94 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



does not long survive removal from its habitat, is seldom 

 seen living in the tanks. Specimens of this, and of several 

 related species, may, however, be seen in one of the 

 Museum cases in the gallery. 



Holothurids, Sea-cucumbers : The commonest local 

 representative of this group is Cucumaria planci (fig. 

 Till., 4), an elongated, worm-like animal, with a mouth 

 surrounded by a crown of tentacles at one end, while rows 

 of tube-feet with suckers run down the five angles of the 

 body. The tough, leathery skin is strengthened by 

 calcareous plates. Another species, Synapta digitata, is 

 occasionally found burrowing in the sandy gravel at low 

 tide. It has anchor-shaped spicules in the skin, and no 

 tube-feet. Other sea-cucumbers are dredged from deep 

 water. The calcareous plates in the skin of some form 

 beautiful objects under the microscope. 



The eggs of all these common Echinoderms develop 

 first into minute larvae which are quite unlike the parents 

 in appearance and structure, and are found floating on the 

 surface of the sea. A larval Ophiurid, called " Pluteus," 

 is seen ai 8, and a larval star-fish, called " Bipinnaria," 

 at 7, on fig. XII. 



Mr. II. C. Chadwick, the Curator of the Biological 

 Station, is our local authority on Echinodermata, and has 

 written a Memoir on Echinus and several oilier papers for 

 our scries of volumes. 



V E RMES. 



(Figs. IX. and X.) 



There are very many kinds of marine worms. Some 



are microscopic, some are parasitic in or on other animals, 



ami some are lowly developed and very sluggish, and 



