ZOOLOaY AND BOTANY, MICROSCOPY, ETC. 67 



different regions of tbe eartli's surface, and that their resemblances 

 to one another are due to the similar conditions of their new and 

 altered mode of life. Some of these modifications have been 

 acquired (e. g. gemmules) and may be said to be of a positive 

 character, while others are negative, and are due to the disappear- 

 ance of some of the characters of their marine allies ; such is the 

 loss of colour, owing no doubt to the disappearance of the conditions 

 for self-protection which called it into existence. The fresh-water 

 sponges may form the group Potamospongiee among the Eenierinse. 



Three species of the new genus Potamolepis are described : 

 P. leubnitzioB, P. chartaria, and P. pechuelii ; they have no resemblance 

 to Spongilla, or indeed to any Eenierine sponge. The last species 

 calls to mind a Farrea, owing to the macroscopic structure of its 

 skeleton, and the arrangement of its fibres. The differences appear 

 to be due to their surroundings, for the currents of water in the rainy 

 season being of great force, it is necessary for Potamolepis to develops 

 structures which are not necessary to the Spongilla of stagnant or 

 gently flowing water. 



Protozoa. 



Parasitic Infusoria.* — Trichomonas vaginalis is described by 

 G. Kiinstler as extremely protean in external form ; it may develops 

 pseudopodia over the general surface or localized at the posterior 

 extremity ; at the anterior end are four flagella united by their 

 bases, from which point an undulating membrane extends to the pos- 

 terior extremity of the body. At the base of the flagella also the 

 mouth opens ; the nucleus, which varies in form, lies at the side of the 

 oesophagus ; the general protoplasm has a vacuolated structure. In 

 the intestine of a certain Chelonian occurs a parasite apparently 

 allied to Giardia agilis. The body is divided into two regions : the 

 anterior is the larger, is vacuolated, and invested by a loose plicated 

 and embossed sheath ; the base of the flagellum has almost the same 

 diameter as the body, is very long, and is readily shown to be striated ; 

 it reproduces by buds from the anterior extremity. Other organisms 

 are mentioned as parasites, but not described, from the same host. 

 Heteromita — or Boda (Bodo ?) — Lacertce is described as a new species 

 from the intestine of Lacerta viridis ; the mouth is surrounded by 

 a circular cushion, the nucleus often has a very complicated structure, 

 presenting much variation, the body is areolar ; reproduction takes 

 place by transverse fission. A pyriform Flagellate, with four long 

 locomotor flagella, with a lobule at their base, leading into the 

 oesophagus, and a longitudinal costa on the left side, also occurs here. 

 A quadri-flagellate organism with a large posterior vacuole is described 

 from Hydrophilus, also an Amoeba, which is truly amoebiform only in 

 the young state, afterwards it maintains a finger-like shape and pro- 

 duces pseudopodia only from the anterior region. Flagellata are also 

 indicated from various insects, from Toxopneustes and the blood of 

 Cuvia, a Nyctotherus from Oryctes and a Planarian from Solen, but 

 with no, or but the briefest descriptions. 



* Coraptes Kendus, xcvii. (1883) pp. 75.5-7. 



