SCIENTIFIC SURVEY. 213 



The second group of families, which is called 



Tracheakia, 

 embraces those arachnids which breathe by means of tracheae, or 

 air tubes and do not have more than four ocelli. 



Pseudo-scorpionidae. This family includes Chelifer, a small 

 scorpion-like animal, which has a large, broad, flattened abdomen, 

 distinctly ringed ; and the palpi are much enlarged, bearing a claw 

 at the extremity much like that of a lobster. A species is very 

 common in books and dusty boxes, drawers, &c. 



Phalangidae. Harvest-men, Daddy long-legs. The common 

 long, slender legged, round, oval-bodied spiders, so abundant 

 everywhere out of doors in corners and damp places, and often 

 called by the names above given, are known to every one. The 

 legs* come ofi" easily, and when separated from the body for some 

 time show considerable irritability. 



Acarina. Mites have the head-thorax joined in a mass with the 

 abdomen, and not divided apparently into rings. They are all of 

 small size, some very minute. Trombidium has two horny mandi- 

 bles, which are clawed at the end, included in the labium, which 

 in the mites surrounds the mouth parts, thus forming a tube-like 

 organ. This genus includes the little square velvet red mite, seen 

 generally in the spring in flower beds, or in moss, &e. Another 

 similar kind of red mite is common about decaying matter under 

 stones and sea weed between tide marks on the sea shore. They 

 are mostly parasitic, such as the itch mite. Ixodes, the tick, lives 

 in woods and attaches itself to animals. Many species ( Ga- 

 masus) are found on insects, especially beetles. The species of 

 Hydrachna live on water-bugs, &c. In coming to maturity it 

 passes through forms which have been described as distinct genera 

 by authors. They should be preserved in small vials of alcohol, or 

 mounted for the microscope. 



Myriapoda. 



All the species, of which we have but a few in New England, 

 live hidden under stones and sticks, leaves, &c., The larvae when 

 hatched have generally nine rings which afterwards increase in 

 some cases to eight times that number. 



The families are divided into two suborders, of which the first, 

 the GMlopoda, comprises those myriapods which have the body 

 flattened, with a limited number of rings, each of which has a 



