KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 59. N:0 3. 57 



The nephridia show the usual Chama-tyipe with the pericardial tubes separated 

 from each other by intruding lobes from the outer sacs. The oscular funnels are 

 narrow and short, debouch into long ampullae with folded walls and being in contact 

 with each other for a short distance until they attain a narrower shape and sepa- 

 rate. The upper parts of the nephridial tubes rim upwards, embedded on the hinder 

 wall of the outer sacs, in which they open, in the left nephridium at the side of 

 the rectum and in the right one somewhat more below. The right nephridium ex- 

 tends with its upper end only to the side of the rectum, the left one terminates 

 somewhat above it. The outer sacs have strong and large lobes and large bladder- 

 like cells, each with one concretion. Their exteriör openings lie close above the 

 nerve cords and opposite to the genital pores. No traces of pedal retractors were 

 observed. 



The genital glands have the usual position behind and outside the liver and 

 are, as usual, formed of tubes with numerous branches. They debouch through a 

 pair of small papillae in front of the nephroprocts. 



Chama coralloides Reeve. 



Figs. 70, 71. 



The statements given below are based on some specimens from Panama. 



External morpliology (fig. 70). 



The mantle is considerably thick över the whole body, especially at the apex 

 of the left umbo, which is formed exclusively by the thickened mantle. The under 

 margins of the mantle are, as usual, coalesced, except the siphonal and the pedal 

 openings ; the two former ones occupy together half the length of the under margin 

 (up to about 2 /3 of it). The expiratory opening is very large (its diameter as long 

 as or longer than half the posterior adductor); the inspiratory one is narrow, and 

 the pedal slit has a length about 1 Ja of that of the anterior adductor. A strong 

 siphonal fold projects beneath the expiratory opening. Between the siphons and in 

 their margins small and dense papillae are present. 



The adductor muscles vary in size, being sometimes (in young specimens) 

 almost uniform, in other cases (as in the specimen figured) very unequal in size, 

 the anterior adductor being twice as broad and twice as long as the posterior one 

 and equal to the space between the upper ends of the adductors. 



Of the labial palps the left ones have been displaced far above and are 

 situated just above the level of the right umbones. On both sides their tips 

 are directed backwards and their whole length is only about ] /s of the anterior 

 adductor. 



K. Sv. Vet. Akad. Handl. Band 59. N:o 3. 8 



