Five New Floscules, &c. By Dr. Hudson. 169 



and wall of the body is occupied by the oTaries and ova, and that 

 in the vicinity of the lower extremity of the stomach there were 

 several yellow spherical balls. Most of the individuals observed 

 were without a case, but in two instances the animal was included 

 in a " copious colourless gelatinous sheath," and had also adherent 

 a large bunch of eggs, in one of which were as many as fifty. 



It is clear from this description that Acydus inquietus re- 

 sembles the Floscules in many respects. Its " oral cup " with the 

 " incurved beak " may be fairly said to be the buccal funnel of a 

 Floscule reduced to the possession of one lobe, viz. the dorsal one. 

 The " oral pouch " in the wrinkled neck is the counterpart of " the 

 vestibule " of the Floscules, just above which, and generally hidden 

 by the wrinkles, lies the true rotatory organ, and at the base of 

 which is the true mouth. In both genera there are minute jaws 

 just below the vestibule ; in both the buccal funnel is retracted by 

 longitudinal muscles, which take their origin in its outer rim, 

 spread over its wall, and pass down the body right to the end of 

 the peduncle ; and in both the buccal funnel is expanded by means 

 of a fluid driven into spaces between the cuticle and dermis. To 

 complete the points of resemblance Acydus is attached when adult, 

 and is occasionally surrounded by a gelatinous sheath, in which lie 

 the extruded eggs. 



The main differences are the entire absence of setse from the 

 rim of the buccal funnel, the apparent lack of any vibratile cilia, 

 the edging of the buccal funnel with a dehcate membrane, and the 

 presence of about twenty parallel teeth in the jaws. 



The first of these differences is not one of much importance, for 

 the length of the setae differs remarkably in the various species of 

 Floscules. In some — as in F. ornata and F. campanulata — they 

 extend to quite the length of the animal's body, while in F. Hoodii 

 they are hardly half the width of the buccal funnel ; and Mr. Hood 

 thinks he has seen on several occasions a new species in which they 

 are shorter still. The membranous edge of the buccal funnel and 

 the numerous teeth in the jaws clearly mark off Acydus from Flos- 

 cularia, but the still more striking difference, viz. the absence of a 

 rotatory organ, may, I think, be only an apparent one. As I have 

 already remarked, this organ consists of a ciliated horseshoe-shaped 

 ridge on the ventral side of the buccal funnel, just where it joins the 

 vestibule, and it is in some species continued down the vestibule in 

 two lines towards the mouth. 



In most of the species it can only be seen in some fortunate 

 position of an unusually transparent specimen ; but in F. trifolium 

 and F. Hoodii it is quite easy to make it out. Now, considering the 

 difficult circumstances under which Professor Leidy saw Acydus, 

 its restless habits, and its thickly-wrinkled cuticle, it is not impos- 

 sible that this rotatory organ may have been overlooked. 



