18 THE EOTIFERA. 



S. GYRINA, Hood (176). This marine Eotiferon was found in spring time by Mr. Hood 

 in a tide-pool in the estuary of the Tay along with Mytilia tavina, Notholca spinifera, 

 and Distemma raptor. It disappeared throughout the summer and winter months, but 

 reappeared in abundance in the following spring. It is so like Synchceta baltica that I 

 hesitate to give it specific rank. The following are the points of difference which appear 

 to separate the two in some degree. The body in Mr. Hood's drawing is narrower, just 

 below the auricles, than it is further down ; and from there it swells out till the middle 

 of the animal is reached, from which point it again diminishes, and then suddenly lessens 

 to form a base to the true foot. Both Ehrenberg and Mr. Gosse draw S. baltica as much 

 more conical, and as gradually tapering to the foot. Mr. Hood says that it does not carry 

 its eggs, as baltica does, but lays them at the bottom of the pool, on confervae &c. Its 

 mode of swimming is peculiar ; for it swims always in circles : sometimes in wide ones, 

 sometimes in circles not much exceeding its own length in their diameter, and it never 

 swims head over heels, as baltica, cr pectinata, does. 



The male is very slender, not over ^^ inch in length ; with a broad corona and a 

 pair of conspicuous red eyes. Mr. Hood observed the connection of the sexes, which 

 took place while the female was in rapid motion, and lasted more than one minute ; he 

 also observed that the males had connection with young females only, never with the 

 full grown. 



Length, (of female) ^ inch. Habitat. Tide pools, estuary of the Tay (J.H.). 



POLYARTHRA HEXAPTERA, Schmarda (135). Schmarda found this Eotiferon in the great 

 clay vessels of drinking water at Paita and Guyaquil. He says that on each side of the 

 body three bristle-shaped spines spring from a common base ; and that there are three 

 teeth in each " maxilla." His figure (in other respects worthless) shows spines very 

 similar to those in Ehrenberg's figure of trigla (see vol. ii. p. 3, note) ; so possibly there 

 may be a Polyarthra with spines like those of a Triarthra : but his statement that there 

 are three teeth in each " maxilla " is incomprehensible ; unless (which is highly impro- 

 bable) the trophi of his Polyarthra are on a different plan from those of platyptera, 

 Length. About ^u inch. 



TRIARTHRA TERMINALIS, Plate (126). 



SP. CH. Base of the unpaired spine, at the posterior extremity of the body ; the 

 spine itself almost immovable, and lying in a line with the, ventral surface. 



Dr. Plate (loc. cit.) says that terminalis resembles longiseta in many respects, but 

 differs from it in having the lowest of its three spines seated at the hinder end of the 

 body, so that its base projects even beyond the orifice of the cloaca. Moreover, this 

 spine does not move with the front pair, but generally remains extended hi a line with 

 the ventral surface. The length of the spines is variable, but Dr. Plate found that in 

 many examples the length of the front pair was thrice that of the body ; of the unpaired 

 spine, twice : all three were usually free from imbrications, whereas those of longiseta 

 are imbricated. 



length, T i T o inch. Habitat. Bonn (Plate). 



T. CORXUTA, Weisse (126) = T. breviseta. 



HYDATINA BRACHYDACTYLA, Ehrenberg (42). SP. CH. 'Body suddenly diminished 

 at the base of the foot ; toes minute" A very doubtful species. It was only T inch 

 in length, and was probably not adult. Ehrenberg's drawing adds nothing to his 

 description. 



H. CHIIYKNSIS, Schmarda (135). The points of difference said to exist between this and 

 IT. wiifa, are that there arc five teeth in each uncus, that the toes are longer, and that 



