18 THE VOYAGE OF H.M.S. CHALLENGER. 



its conveniently small size I selected the latter species for anatomical study by means of 

 transverse sections, which I found much better than dissection owing to the state of 

 preservation of the specimens. 



On PI. X. fig. 6 is figured a transverse section through the head of Sei'olis septem- 

 carinata showing the salivary glands in situ; a is the aperture of the mouth, h the buccal 

 cavity, and c points to the ventral wall of the body bounding the mouth ; the salivary 

 glands [d) are arranged in rosette-shaped aggregations of cells surrounding a central 

 cavity ; these cells are highly granular, and stain deeply with carmine ; each is j^rovided 

 with a large nucleus which stains rather more deeply than the surrounding protoplasm ; 

 the glands are imbedded in the cellular connective tissue of the body, some of the cells 

 of which are shown in the figure (e). Similar structures have been observed by Dohrn ^ 

 in Anceus and Parantliura, and are figured and described by him in his account of the 

 anatomy of these two genera. 



The oesophagus, as in other Crustacea, passes upwards into the masticatory stomach, 

 which is furnished with a complicated series of chitinous plates. 



On PI. X. fig. 9 is figured the masticatory stomach of Serolis hromleyana viewed from 

 beneath ; the " pyloric "end is directed towards the upper margin of the plate. 



There is an ujjper median azygos cardiac plate {m) ; in front of this and below is a 

 cylindrical plate (LR, RP) on either side ("Eeibe-platte"), the lower surface of which is 

 traversed by a row of rib-like thickenings. On either side of the median plate are three 

 lateral plates {I, la, Ijj), one median, one anterior, and one posterior ; the median lateral 

 plate (I) is furnished with numerous fine hair-like processes on the under surface. On 

 the ventral surface of the stomach is a large ossicle ( F) which reaches beyond the 

 commencement of the dorsal azygos piece (wi), and terminates in a bifurcate extremity ; 

 behind this comes the j^yloric portion of the stomach, which has four ossicles on either 

 side; two small triangular ossicles (t), situated just above the median piece (F), and 

 behind three pairs of elongated ossicles which are furnished with delicate hairs directed 

 inwards and form a sieve-like structure ; the outermost ossicle (2) is connected both with 

 the median ventral ossicle ( F) and the lateral plate (R-P.) of its own side ; s points to the 

 pyloric^aperture. 



In Serolis antarctica the masticatory stomach is entirely similar. 

 • In Serolis ixiradoxa the masticatory stomach apparently differs from that which has 

 just been described by the very incomplete calcification of the cardiac ossicle, which is 

 indeed hardly to be recognised as a distinct ossicle ; the ventral median ossicle does 

 not extend so far backwards as in Serolis hromleyana, and is less markedly emarginate 

 at its apex. 



The masticatory stomach in the two other species in which I have studied it, viz., 



1 Entwickelunr; und Organisation von Praniza (Anceu.s) uiaxillaris, Zcitschr. f. wiss. ZooL, Bd. xx. p. 55, 1870 ; and 

 also Zur Kenntniss des Baues von Paruuthura cos^taua, Ibid., p. 81. 



