EEPOET ON THE RADIOLAEIA. 929 



Subfamily 4. Polypleotida, Haeckel, 1881, Prodromus, p. 424. 

 Definition. — P 1 e c t a n i d a witli numerous (seven to nine or more) radial spines. 



Genus 400. Polyplecta,^ Haeckel. 



Definition. — P 1 e c t a n i d a with numerous (seven to nine or more) radial spuies, 

 arising from a common centre and lying in different planes. 



The genus Polyplecta comprises provisionally all Plectanida possessing seven or 

 more radial spines, united in the centre of the framework. It may be derived from 

 Polyplagia by meeting and concrescence of the free branches. But as in the latter 

 genus, here also the few observed species are very different, perhaps of different origin, 

 and may be afterwards better separated as representatives of diverse genera. 



1. Poli/plecta heptacantha, n. sp. (PI. 91, fig. 12). 



Heptaplegma heptacantha, Haeckel, 1882, MS. 



Seven unequal spines divergent from one common central point, slender, slightly curved, three- 

 sided prismatic. Four spines are much larger, twice to three times as long and as thick as the 

 three smaller spines. One of the four larger spines is directed upwards (as " apical horn "), whilst 

 the three others diverge downwards (as " basal feet "). Each of the four larger spuies bears five to 

 seven equidistant verticils of three divergent branches, the proximal of which are branched, the 

 distal simple. The three smaller spines He nearly horizontally, midway between the odd apical 

 spine and the three basal spines, and in the same meridian planes with them ; each bears one 

 verticil of three divergent branches. All the branches are united by arachnoidal threads, composing 

 a loose wickerwork with irregular, generally quadrangular meshes. 



Dimensions. — Length of the four larger spines 0'27 to 0'33, of the four smaller 01 to 014 



Habited. — Central Pacific, Station 271, surface. 



2. Polyplecta emieacantha, n. sp. 



Enneaplerjina enneacantha, Haeckel, 1881, Prodromus, p. 425. 



Mne equal and equidistant, straight, cylindrical radial spines, lying nearly in one plane, arise 

 from an irregular spongy central framework; six , of them seem to be secondary, intercalated 

 between three equidistant primary spines, which are united in the centre. (This species resembles 

 in the nine-radial structure the remarkable EnneaphorTnis rotula, PI. 57, fig. 9, and may perhaps 

 be derived from a similar species ; but it has no regular latticed shell.) 



Dimensions. — Length of the spines 0'22, diameter of the framework 017. 



Habitat. — Central Pacific, Station 266, depth 2750 fathoms. 



1 Polyplecta = M.\i(h. entwined ; ttoAi/ttAsxtoj. 

 (ZOOL. CHALL. EXP.— PART XL. — 1886.) Er 117 



