The Genus Synchceta. By C. F. Rousselet. 411 



in June in immense swarms, when the sea has been very calm for 

 a long time, but not every year. Mr. Jennings' preserved material, 

 prepared for the purpose of studying the segmentation and develop- 

 ment in the egg, is not very good as regards the adult Synchreta, 

 the great majority of the animals being badly contracted, but by 

 searching some fairly extended specimens have been secured, of 

 which the following is a description : — 



The body is top or cone-shaped, either straight or slightly 

 swollen at the sides. The front part of the head is broad and 

 rounded, and bears four styles, the outer pair arising from 

 triangular fleshy flaps, and auricles of fairly large size. The 

 foot has two distinct joints, and carries a spur-like process at its 

 dorsal end. It ^is somewhat difficult to decide whether this pro- 

 cess is a true spur, an organ otherwise unknown in this genus, or 

 a second toe turned upwards, and to some extent gone out of use. 

 The process is situated on the dorsal side of the second joint of 

 the foot, but to the left of the median line, and originates a little 

 higher than the base of the true toe, which seems to be the only 

 exit for the secretion of the large and apparently single foot-gland. 

 Whatever its true meaning, this structure forms the most pro- 

 minent distinctive character of this species, and fig. 9a gives an 

 enlarged view of the foot and spur-like structure. 



The mastax is of usual Synchseta shape and structure, the unci 

 have teeth similar to those of S. oblong a, but their exact number 

 could not be ascertained in the preserved specimen. The stomach 

 is not large, of usual structure, and carries two rounded gastric 

 glands. A rounded ovary, contractile vesicle, and lateral canals 

 are present. The cervical eye is single, with occasionally a slight 

 appearance of splitting in two halves, but I could see no trace of 

 frontal eyes .such as S. triophthalma possesses. The dorsal antenna 

 is situated on a fleshy projection above the eye, and the lateral 

 antennae are very small and protrude at a point about two-thirds 

 down the side of the body and slightly on the ventral side. 



In life the eggs are carried about attached to the toes. I found 

 a large number of both male and female eggs in the preserved 

 material, and also the male, which is of usual structure and repre- 

 sented in figs. 95 and 9c, dorsal and lateral view. 



Mr. F. R Dixon-Nuttall has made a good drawing of both 

 male and female, figs. 9a, b, and c, after looking at and comparing 

 a number of specimens which were not too well preserved. 



The size of the female varies considerably, as usual, from 109 p, 



(dr in -) t0 163 /* (ts5 ™0 lon S °y 75 f- (sh in -) t0 108 H> (sh in -) 

 wide at the auricles. The Male is 75 /a (g^ in.) long. The eggs 



are oval in shape and measure : — female eggs, 61 ^ (^\^ in.) long 



by 51 fi ( 5 J in.) broad; male eggs, 44 fi (5)3 in.) long by 34 /a 



(jIq in.) broad. 



2 e 2 



