[439] INVERTEBRATE ANIMALS OF VINEYARD SOUND, ETC. 145 



of Cancer irroratm, (p. 312, Plate VIII, figs. 37, 37a,) and of Platy- 

 onichus in the zoea and mega-lops stages, were taken in vast numbers, 

 especially in bright sunshine, together with similar larvse of many 

 other species. The larvre and young of the lobster (Plate IX, figs. 38, 

 39) were also abundant in mid-summer. The numerous specimens ob 

 tained have enabled Mr. S. I. Smith to describe the interesting meta 

 morphoses of our lobster, which were entirely unknown before. The 

 young swim actively at the surface, like a shrimp, until more than half 

 an inch long. The larvre and young of the various species of shrimps 

 are also abundant. The curious larvae of Squitta empusa (Plate VIII, 

 fig. 36) were often met with. 



Several species of Amphipods are also common at the surface. The 

 most abundant were Calliopius Icevimculus, of which Mr. V.K Edwards 

 also took numerous large specimens in February and March ; Qammarus 

 natator^ which was usually common, and occurred in immense numbers 

 August 10 and on several other occasions ; and a Hyper-ia, which infests 

 several species of large jelly-fishes, and also swims free at will. The 

 Phronima- is a related genus, but is very remarkable for its extreme 

 transparency, which renders it almost invisible in water. Idotea irro- 

 rata (p. 316, Plate V, fig. 23) and I. robusta, Plate V, fig. 24) were 

 very common among masses of floating eel-grass and sea- weeds, and 

 the latter was also very often found swimming entirely free. 



A species of 8a&amp;lt;ppliirina (Plate VII, fig. 33) was found in great num 

 bers among Sal-pce, off Gay Head, on several occasions, early in Septem 

 ber. This is one of the most brilliant creatures inhabiting the sea. It 

 reflects the most gorgeous colors, blue, red, purple, and green, like fire- 

 opal, although when seen in some positions, by transmitted light, it 

 is colorless and almost transparent. Under the microscope, when 

 living, it is a splendid object, whether seen by transmitted or reflected 

 light, the colors constantly changing, as it is turned in different posi 

 tions. When seen beneath the surface of the sea, in large numbers, 

 the appearance is very singular, for each one as it turns in the right po 

 sition reflects a bright gleam of light, of some brilliant color, and then 

 immediately becomes invisible, and these scintillations come from dif 

 ferent directions and various depths, many of them being much farther 

 beneath the surface than any less brilliant object could be seen. In 

 some cases one or more were found in the branchial cavity of 8alpce 7 

 but whether this is normal or accidental was not determined. 



The species of Argulus are parasitic on the exterior of fishes, but we 

 found at least three species swimming free at the surface. It is, there 

 fore, probable that they are able to leave their hosts for a time, and 

 thus to migrate from one fish to another. The species of Caligus are also 

 parasites on fishes, to which they firmly adhere, but the half-grown 

 young of one species was taken at the surface in the towing-nets. 



Numerous species pf Annelids, in the larval and young stages, were 

 taken at the surface, but many of them have not yet been identified, 



