2 Dr. R. GrccfF on the Annelid Genus Sphserodorum, 



liarities that may render it worth a particular description ■^. I 

 will revert at the conclusion of my communication to the cha- 

 racters common to this worm and to Sphcerodorum, as also to 

 those by which it differs therefrom, in order the better to 

 effect a comparison between them. 



The little animal measures scarcely 2 millims. in length, but is 

 of considerable comparative breadth, attaining nearly 0'6 miliim. 

 in the middle regions of the body. It is narrowed before and 

 behind in such a manner that the general form of the body, 

 leaving out of consideration the external appendages, approaches 

 an oval ; nevertheless the narrowed anterior part of the body 

 is shorter and more rounded, whilst the hinder part appears 

 more drawn out. The skin has a general light brownish- 

 yellow colour, with dark-brown marks {jjlaques) distributed 

 singly over the whole surface of the body ; these acquire the 

 most various forms, and possibly represent the secretion pro- 

 duced by the cutaneous glands. At no part is there a trans- 

 verse segmentation of the body indicated by external furrows. 

 The segmentation, however, is sufficiently indicated by the ex- 

 ternal appendages, according to which the entire body is divisible 

 into 18 segments. The cephalic segment (see PI. I. fig. 1), 

 which at first sight almost presents a greater resemblance 

 to that of a mollusk than to that of an annelid, is the longest 

 of all ; its somewhat truncated frontal margin presents in the 

 middle a distinct but not deep notch forming the two lateral 

 lobes of the head. On each lobe are seated two clavate tenta- 

 cles — one placed more towards the upper surface, the other 

 lower down towards the mouth ; so that, in all, four cephalic or 

 frontal tentacles are present — two superior, and two inferior. 

 The bases of these, as also the space between them, are densely 

 set with small papillae, likewise more or less clavate, which are 

 distinguished from the true tentacles by nothing but their 

 smaller size ; so that the tentacles, from their whole habit and 

 when compared with the small papillae surrounding them, 

 might likewise be characterized as papillre projecting, in conse- 

 quence of especial development, from the midst of the numerous 

 smaller but otherwise perfectly similar structures. But their 

 constant occurrence on the above-mentioned spots on the head, 

 their size, and mobility justify their receiving the denomination 

 of tentacles. 



Further back, at about half the length of the head, there are 



* I have alrcr.dy made a brief comuiimication upon this subject, at 

 the fleeting of the Niederrheiuischeu Gesellschaft fiir Natur- und Ileil- 

 kunde (Bonn) on the 8th February, 18()6, where I also exhibited the 

 drawings reLiting to it (Kohiisehe Zeitung, i3lst March, 1S66, No, 90). 



