REPORT ON THE DEEP-SEA MEDUSAE. 87 



teral triangle, 36 mm. in height, 32 mm. at base, whose truncated point reaches as far as 

 the middle of the genitalia, and is there inserted at the interradial septal node (hi). The 

 muscular fibres which diverge radially from its point towards the base are nearly equally 

 powerful throughout. The narrow " musculus intergenitalis " (ms) above, between the two 

 genitalia of each pair, is formed by a weaker process of this deltoid muscle. The perradial 

 deltoid muscle (md') is weaker than the interradial; it forms an equilateral triangle 20 mm. 

 in height, 25 mm. at base, whose truncated point reaches as far as the oral end of the 

 gastral opening (go), and is inserted there below the palatine groove (gs) at the perradial 

 palatine node (gk). The lateral muscular fibres (md'") are much more strongly developed 

 in this muscle than in the median muscles. A band-shaped "musculus congenitalis" (mp) 

 springs from each side of the perradial deltoid muscle ; it lies coradially between the outer 

 margin of each genitalium (s) and the gastral opening (go), and extends to the upper end 

 of the latter. This band-shaped congenital muscle is 1 mm. broad below, 5 mm. broad 

 above ; its length amounts to 60 mm. Its fibres which run parallel, and only converge 

 slightly above, spring from the lateral margin of the perradial deltoid muscles, and are 

 inserted above at the pyloric opening (gy). 



The broad coronal muscle (fig. 1, mc) shows essentially the same condition as that 

 already described in Periphylla mirabilis (p. 71). Its proximal margin (mc) serves 

 as a basis of origin for the deltoid muscles. Its subumbral surface is elevated into 

 10 to 12 circular folds (mc 2 ) with deep furrows sunk between them (mc 3 ). The coronal 

 muscle is also divided by the sixteen subradial lobe clasps into sixteen coronal arese. 

 These are 25 mm. high in the middle (between each two marginal lobes), but 30 mm. 

 high laterally in the middle of each marginal lobe. The four ocular muscular area? 

 (25 mm. broad) are only a little smaller than the twelve tentacular coronal area? 

 (30 mm. broad). The intermediate lobe clasps are much weaker than in the preceding 

 species, but show the same structure in transverse section (fibrous cartilage, PI. XXV. 

 figs. 9, 10). The formation of the lower or distal margin of the coronal muscle (PI. 

 XXIV. fig. 1, wm; 4 ) is peculiarly differentiated. Whilst in Periphylla mirabilis it is 

 quite smooth, projects internally like an umbrella roof over the insertion of the tentacles, 

 and forms a simple tentacle funnel (it), in Periphema regina it is fringed and divided 

 into numerous fine folded lobes or " frenula." On each of the sixteen muscular arese 

 there are nearly twenty such frenula, 2-3 mm. long, which connect the distal margin of 

 the muscle with the subumbral surface of the marginal lobe lying below it. An equal 

 number of subumbral funnel-shaped depressions are deeply inserted between these 

 frenula in the thickened distal margin (" infundibula subcoronaria "). 



Both parts of the umbrella cavity, the lower simple coronal umbrella cavity and 

 the upper quadrilocular funnel umbrella cavity, comport themselves the same on the 

 whole in Periphema regina as in Periphylla mirabilis. The simple coronal umbrella 

 cavity forms a circular hollow space, whose subumbral external wall forms the umbrella 



