10 Transactions of the Society. 



the teeth and the spurs. The papilla; of M. scarlatina are scattered, 

 not close together. They are irregular in size, and some are larger 

 than those of M. scabrosa. It has more numerous teeth, eight, 

 nine, or more. The spurs are short, conical, acuminate or ohtuse, 

 and separated by a wide interspace. 



Habitat. — Uganda (N". D. F. Pearce), Kikuyu (A. Allan), New 

 Zealand and Australia (Brit. Antarct. Exped. 1907-9). 



In Queensland it attained to a length of liOO/t when creeping. 



Habrotrocha caudata sp. n. Plate I. figs, la-le. 



Specific characters. — Small ; antenna and rostrum short ; corona 

 small, disks close : lower lip spout-like ; teeth, about four in each 

 jaw ; a long curved, tail-like process at posterior part of central 

 trunk ; a smaller process of anus ; spurs minute, narrow, acute ; 

 inhabits a brown case open at each end, the neck narrow and 

 curved, the posterior tube to accommodate the tail. 



General description. — Length when feeding about 170/x; case 

 120/z long, by 70/a diameter at widest part. The head is shaped 

 like that of Habrotrocha angusticollis, the lower lip forming a pro- 

 minent spout. The length of the antenna is equal to rather less 

 than half the diameter of the neck. The rostrum is short and the 

 lamella? small. The neck is less elongate than that of H angusti- 

 collis. There are prominences on each side of the antenna. The 

 trunk segments are so indistinct that it is not easy to tell which of 

 them bears the dorsal process or " tail." It is probably on the 

 4th-central segment or the preanal, possibly between the two. 

 The tail appears to be tubular, but whether there is any opening 

 at the end could not be ascertained. It is strongly curved, with 

 the concavity on the anterior side. It can be partly inverted at 

 the tip by the action of special muscles, and is shown truncate 

 from this cause in fig. Id. The process behind the anus is a small 

 rounded flap, which appears ovate and acute in lateral optical section. 



The foot is very short, but appears from slight swellings to con- 

 sist of three segments from the anus to the spurs. The toes 

 have not been seen. The spurs have not been seen in dorsal view. 

 Seen from the side they are short, sharp, and curved downwards. 

 There are usually four teeth, diminishing in thickness, with one 

 thinner and many fine stria?. The thicker teeth may vary from 

 three to five. The general form of the case is like that of H. an- 

 gusticollis {14), but it is smaller, and has the neck strongly curved 

 towards the dorsal side, with a smaller opening. The posterior tube 

 is set on nearly at right angles to the axis of the trunk, or inclined 

 slightly forward at the free end. It is nearly straight and of uniform 

 thickness ; length about 40 /j.. 



There are many things in the organization of this extremely 

 interesting species which await explanation. The peculiar case, 



