189 t.] NEW-YORK MICROSCOPICAL SOCIETY. 57 



among the Crustacea. At present they are placed between the 

 mites and spiders among the Arachnida, although they possess 

 a greater number of appendages than either, inasmuch as the 

 males have an accessory pair of legs, used in carrying the eggs. 

 They are small animals with a conical suctorial proboscis, and 

 rudimentary abdomen reduced to a tubercle. They live in the 

 sea, and crawl slowly about amongst the seaweeds. They have 

 four pairs of very long many jointed legs, which contain tubu- 

 lar diverticula of the stomach and the sexual organs. They 

 have no tracheae, but have a well-developed heart with an aorta 

 and several lateral ostia. Above the brain lie four small simple 

 eyes. They have a considerably extended ventral chain, com- 

 posed of several glanglia. The eggs are carried on the acces- 

 sory pair of legs on the thorax of the male, until the larvae are 

 hatched. 



" Obelia conimissuralis is a Hydromedusa, belonging to the 

 Polynomedusje, or Hydrozoa. The individual polyps are joined 

 in a colony. The chitinous tubes widen out around the head 

 to form a cup-like hydrotheca. The head, the oral cone and 

 the tentacles can be retracted into the hydrotheca. The genera- 

 tive buds arise on the walls of the proliferous individuals, 

 which have neither mouth nor tentacles. The buds form, in 

 Obelia, flat, disk-shaped Medusae, with numerous marginal 

 tentacles, but with eight inter-radial vesicles. The urn-shaped 

 reproductive capsules discharge the small Medusae, and these 

 swim freely for some time, until they fasten to suitable places 

 and form new colonies. The Hydromedusae feed entirely upon 

 animal substances, and are most common in warm seas. The 

 free moving Medusae are phosphorescent. Obelia occurs at 

 low water mark and in tide-pools, attached to stones and sea- 

 weeds. It is very delicate and much branched, and sometimes 

 grows five or six inches high, though usually smaller." 



Mr. Zabriskie said of his exhibits : " The Pseudo-scorpions 

 are distinguished from the true scorpions by the absence of a 

 tail and by a difference in the mode of respiration. They are 

 related to the spiders, spin a web for protection during moulting 

 and hybernating, and are classified with the Arachnida. They 

 have two pairs of pincers : a large pair, the palpi, extending on 

 either side, and a small pair, the falces, lying close together in 

 front of the head. 



