INVERTEBRATE AXIMALS OF YIXEYARD SOUXD, ETC. D i\) 



stantly sbadeil, very few alga?, and those only of the smallest and sim- 

 plest kinds, sueli as Ocillatoriiie and Diatoms, are to be fonnd. But in 

 these shaded situations many animals, such as Tubularians and other 

 Hydroids, some Ascidians, Bryozoa, &c.j delight to dwell. Many of 

 these adherent animals also live in abundance on the outermost piles of 

 the wharves, at or just below low-water mark, where they are more or 

 less exposed to the sunlight. 



The animals that are found among or attached to the seaweeds 

 growing on the i:)iles are, for the most part, identical with those that 

 are to be found in similar situations among the algi^ on rocks and in 

 rocky tide-pools. 



Among those that are nearly or quite peculiar to submerged wood-work 

 are several species of " ship-worms,'' {Teredo of several species, and the 

 Xylotrya fimhriata^) which are bivalve mollusks; the wood-eating Lim- 

 noria; several species of barnacles, which belong to the Crustacea; 

 some of the tubularians, and other hydroids, &c. 



Of the salt-water Insects two species have been observed on the piles 

 of whar\'es. One of these is a small, slender, green larva, with a dark, 

 firm head, and sharp jaws. It is the larva of a small, two-winged fly, 

 probably identical with the Cliironomus oceanicus of Packard. 



On the piles of a wharf at Menemsha, Dr. Edward Palmer found, in 

 October, a very interesting insect-larva. It lived in a stout tube com- 

 posed of grains of sand firmly cemented together, and attached by its 

 whole length to the piles; the single si)ecimen is broken at both ends. 

 The tube is flattened, and consists of a central, subcylindrical, tapering 

 portion, or i^roper tube, which is covered on all sides with a single layer 

 of small grains of sand, neatly arranged ; along each side of this, and 

 partly covering its upper surface, and to fill the angle between it and 

 the surface to which it was attached, larger grains of sand are cemented. 

 The preserved portion of the tube is about three-quarters of an inch 

 long and nearly one-quarter wide, at the larger end, but not more than 

 half as wide at the small end. The larva is about a third of an inch 

 long, rather stout, and has a pair of long, sharp, curved jaws, and three 

 pairs of rather long, hairy legs. It belongs to the Phryganid?e, among 

 the Xeuroptera, and somewhat resembles some of the well-known larva? 

 of the caddis-flies, common in fresh water, which make tubes or cases 

 of various kinds. Dr. Hagen, who has examined this specimen, refers 

 it to the genus MoJanna, of which three iS'orth American species are 

 known, but only in the adult state. All the larvic of this genus, known 

 in Europe, live in fresh water, and no other species of the Phryganidi^. 

 has been observed in sea-water, although some live in water that is 

 slightly brackish. 



Of Crustacea the most important species is the Limnoria lignorum, 

 (p. 370, Plate Tl, fig. 25.) This little creature is grayish in color, and 

 covered with minute hairs. It has the habit of eating burrows for 

 itself into solid wood to the depth of about half an inch. These bur- 



