8 



PROCEEDINGS OF THE NATIONAL MUSEUM 



VOL. 73 



LOXOTHYLACUS PANOPAEI (Giwler) 



Sacculina. panopaei Gissleb, 1884 



The animal has a roundish shape; in some cases the mantle has 

 more or less distinctly marked tips'. (Fig. 4.) The size is variable, 

 though in general the parasites of this species are small ; the largest 

 specimen in the collection has a greater diameter of about 6 mm. 



The mantle opening lies at the top of a small tube-like expansion 



of the mantle, which is usually directed towards the surface which 



-lies against the thorax of the host. In the type specimen (see 



C 



X 



jtS^^^ ^ 



Fig. 4. — Two specimens of Loxothylacus panopaei (Giss- 

 LEE). a, FROM Panopeus herbstii Milne-Edwards, 



THE SURFACE LYING AGAINST THE THORAX OF THE 

 HOST, X 7I/2. &, THE SAME SPECIMEN, THE SDRFACB 

 LYING AGAINST THE ABDOMEN OF THE HOST, X 7%. C, 

 FROM EORYPANOPEITS DEPRESSUS (SMITH), THE SURFACE 

 LYING AGAINST THE THORAX OF THE HOST, X 7%. d, 

 THE SAME SPECIMEN, THE SURFACE LYING AGAINST THE 

 ABDOMEN OF THE HOST, X 7%. IN THESE FIGURES THE 

 MANTLE OPENING IS FOUND IN THE UPPER PART, THE 

 STALK IN THE LOWER PART 



"Gissler, 1884, figs. 1 and 2) this tubular expansion of the mantle also 

 is well developed. 



In the accompanying figure (fig. 5), a longitudinal section parallel 

 to the dorsal and the ventral surfaces, all the characteristics of the 

 genus Loxothylacus are visible: The stalk is attached to the mantle 

 at some distance from the visceral mass, a section of the closed part 

 of one of the testes is found in the posterior part of the visceral mass, 

 and in the lower part of the figure (consequently in the anterior 

 part of the animal) the visceral mass is attached to the mantle by 

 the mesentery. The section is from the immediate vicinity of the 

 mantle opening, a part of the sphincter which surrounds the mantle 

 opening is visible in the lower part of the figure. 



