REPORT ON THE TUNICATA. 59 



the folds are more constant in number and position. There arc almost always the same 

 number of folds on each side, 1 and that number is either five (Molgula crystallina, 

 Miller), six, or seven — usually the latter. Large papilla' on tin' internal longitudinal 

 bars, like those characteristic of the Ascidiidaa. are never seen. Usually the bars are 

 perfectly smooth, but in a few species minute projections, evidently corresponding t<> 

 papillae, are present. 



In a typical Molgula the arrangement of the stigmata is very peculiar. Each fold 

 projecting from the inner surface of the branchial sac is formed of a longitudinal series 

 of conical bags, having square external bases, and pointed internal apices, which may be 

 branched. The stigmata form spiral slits more or less interrupted, extending from the 

 base to the apex of this bag or infundibulum, as Lacaze-Duthiers names it. 



The flat spaces lying between the rows of infundibula have their stigmata more 

 irregularly arranged, but still curved, and usually having an indistinctly marked spiral 

 disposition. In some of the new forms this typical arrangement is not found, the stigmata 

 being irregularly disposed though still curved, but occasionally almost straight. 



The tentacles are compound, and are very like those of the Cynthinse and Bolteninse. 

 Lacaze-Duthiers mentions as characteristics of tbe Molgulid tentacles the greater number 

 of secondary and tertiary pinnules, their more irregular size, and less tapered extremi- 

 ties, and most important of all the raising up of the membrane covering their inferior 

 or branchial surface into puffed-out projections and folds. 



The appearance of the intestine is rather characteristic of the Molgulidaa. It is firmly 

 attached to the mantle on the left side, and is so sunk in it that it becomes very clearly 

 visible from the outer surface, and seems to be in the middle of the thickness of the mantle. 

 The genitalia are placed on the inner surface of the mantle, and are usually developed 

 on both sides. On the left side the gland is close to the intestine, on its anterior edge, 

 however, not in the loop. The opposite gland, which is absent in the genus Eugyra, 

 occupies the centre of the right side ; while posteriorly to it lies the heart, separating 

 the genital gland from the renal organ, which has rather a characteristic appearance in 

 the Molgulidse, being a compact and more or less solid organ placed near the inner Burface 

 of the mantle towards the posterior end of the right side. 



The following genera have been at various times referred to this family : — Molgula, 

 Eugyra, Ctenicella, Anurella, Glandula, Gymnocystis, Pera, Lithonephrya, Ccesira, 

 and Ascopera. Of these Molgula, Eugyra, and Ascopera are represented in the Chal- 

 lenger collection. 



Ctenicella was founded by Lacaze-Duthiers in 1877, and is probably a good genus. 

 I have found it impossible, however, to accept his Anurella. It is distinguished from all 

 other Molgulidse by the remarkable structure of the larva, which is "amoeboid" and 



1 In Molgula pyriformis (see page 79) there are seven folds on the ri^Ut Bide and six on the left It is possi I 

 however, that this may be an individual peculiarity. 



(ZOOL. CHALL. EXP. PART XVII. 1SSJ.) R 9 



