A Contribut. to the Embryol., Life-history, and Classificat. of the Dicyemida. 13 



3. Dicyema mierooephalum Whit. Pigs. 22 — 29, PI. 2. 



Occurs only in Octopus Be-Filippi^ Ver. Calotte 

 octamerous , orthotropal, broader tlian long, often less 

 wide than the body, evenly rounded. 



The pro poi ars gene rally, sii ghtly s mailer than the 

 metapolars, no difference between the dorsal and ven- 

 tral cells of the sa me polar set. 



The 2 parapolars followed by 2 dorsal and 1 ventral 

 ectodermal celi. 



Ve rr nei form cells — 6. 



Totalnumber of ectodermal cells 26. 



Greatest length recorded 2.5 mm. 



In the majority of cases I bave found the transverse diameter of 

 the head exceeded by the average width of the body, Fig. 22. In one 

 of the larger examples, regarded as a typical representative, the width 

 of the head was .07 mm, that of the body .06 — . 10 mm. 



In many cases the entire ectoderm is charged with granules (»glo- 

 bules refringents« Van Beneden), several cells being more heavily 

 loaded . but otherwise not dififering from the rest. These granular cells 

 par excellence, often apparent in the yoiingest free individuals, are, as 

 a rule , less distinctly verruciform than in other species of the same 

 genus. In one instance the two caudal cells were thus characterized, 

 and much larger than usuai , remiuding of a condition which prevails 

 among a s})ecies found in Sepia officinalis. 



This species, so far as my observations go, is distinguished from 

 ali other species of the genus Dicyema , by the permanent and almost 

 perfect quadrilateral symmetry of its calotte (fig. 22 — 29) . The number 

 of cases examined, however, is not sufficiently large to warrant my 

 sayiug that the species never exhibits the tendency to obliquity noted in 

 ali its congeners. 



4. Dieyema moschatum . Pigs. 1 — 15, PI. 1. 



Confined to Eledone moschata Leach, but not infre- 

 quenti y accompanied by a species belonging to the genus 

 Dicyemeimea [D. Eledones). Calotte octamerous; orthot- 

 ropal in the embryo, in manyof theyounger, and in some 

 of the larger individuals; more or less plag io tro pai in 



