Of course we must begin with the maxillipedes (Fig. 72). The specimen may be held between the finger and thumb, and the parts picked out with a needle. It is, however, better and easier to make the dissection under water. Then we can remove the second and first maxillae, the latter easily recognizable by its palp or feeler. Last of all come the mandibles, also bearing a palp. We shall _feel_ these under the needle, because of their hardened cutting edges. These are distinctly toothed. When practice has made the separation of these parts fairly easy, they should be compared with the mouth parts of other members of the group, so as to utilize the knowledge we have gained. [Illustration: FIG. 72.--Maxillipedes of _Gammarus marinus_ (in centre). _A._ First maxilla. _B._ Second maxilla (magnified).] Next come the two pairs of gnathopods, and in these we have to find seven joints--which may be denoted by the numbers 1, 2, 3, 4, 5, 6, 7; 1 being the basal joint, or that nearest the body. The sixth joint is often called the ‘hand,’ and the seventh, the ‘finger.’ The joints vary greatly in different genera. The walking legs are next to be examined, and we may notice that the first and second pairs are turned forwards, and the third, fourth, and fifth pairs backwards. At the bases of these legs are the breathing apparatus, and the females have leaf-like plates on the anterior four pairs, forming a pouch in which the eggs are hatched, and here she shelters her young, and carries them about with her. The following account of this habit is taken from Bate and Westwood’s _Sessile-eyed Crustaceae_ (i. pp. 380, 381), and was furnished to the authors of that book by Dr. James Salter: ‘On catching a female with live larvae, nothing is seen of the progeny till the parent has become at home in the aquarium, when the little creatures leave her and swim about in her immediate neighbourhood. The plan I have adopted to watch this curious habit of maternal protection, has been to place a single individual in a bottle of sea water. After a time, and that soon, the little crustacean seems at ease and swims slowly about, when the young fry leave her and swarm around her in a perfect cloud; they never leave her for more than half or three-quarters of an inch, and as she slowly moves about they accompany her. If now one taps the side of the bottle with one’s finger-nail, the swarm of larvae rush under their parent, and in a second are out of sight. The parent now becomes excited, and swims about quickly, as if trying to escape; but by letting the bottle containing her rest quite still she soon gets composed, when out come the young larvae again and swim about as before. This may be repeated as often as the observer wishes, and always with the same result. I have only seen this in one species, but it is quite a common species in Poole Harbour, and I have watched the interesting habit many times.’