3T 



sea-waters. To do this, take a circular piece of filtering-paper, 

 six inches or thereabouts in diameter (blotting-paper will answer 

 if the other cannot be procured). Pass a quantity of the water, 

 varying with its turbidity from a pint to a gill, through the paper, 

 and allow this to dry. Mark the paper or its envelop with the 

 amount of water passed through, date, place, &c. It is desirable 

 to have specimens thus prepared for every locality and for every 

 month in the year. They may be sent, as well as light packages 

 of dried muds, &c., by mail, and should be transmitted as speedily 

 as possible. Unless the operation can be performed by an expe- 

 rienced hand, the weighing may be dispensed with. 



When the water of lakes and ponds has been rendered turbid by 

 minute green or brown specks, these should be gathered by filtration 

 through paper or rag, which may then be dried, or, still better, 

 this matter may be scraped off into a small vial of alcohol. 



§ XI. ON THE COLLECTION AND PRESERVATION OF 

 MARINE INVERTEBRATES.* 



Classification. — The animals inhabiting the sea, excluding the 

 fishes and other vertebrates, may be divided, for convenience, into 

 groups, as follows: 1st. Crustaceans, including crabs, hermits or 

 soldier crabs, lobsters, langoustes, cray-fish, camerones, shrimps, 

 prawns, sand-hoppers, beach-fleas, whale-lice, sea-creepers, pill- 

 balls, fish-lice, sea-spiders, water-fleas, gill-suckers, and other para- 

 sites on fish, also barnacles. 2d. Annelids, including all kinds 

 of sea-worms, some of which hide among seaweed and pebbles, 

 but most of which live in mud or sand, many having tubes. 3d. 

 Cephalopods, or cuttle-fishes and squids. 4th. Naked Molluscs, 

 or sea-slugs. 5th. Shells, both bivalve and univalve. 6th. Tuni- 

 CATES, vulgarly called "sea-squirts," consisting simply of leathery 

 balls or sacks of various shapes, with two apertures, often occurring 

 in compound forms. 7th. Bryozoans, or those minute coral-like 

 incrustations found on seaweeds, stones, and old shells. 8th. Holo- 

 thurians, those worm-like or slug-like echinoderms like the biche- 

 le-mer or trepang. 9th. Echini, sea-eggs or sea-urchins, most of 

 which resemble chestnut burrs, being covered with spines. 10th. 

 AsTERiAS and star-fishes of all kinds. 11th. Polyps, including 



* Prepared by Mr. Wm. Stimpson. 



