SYNCRYPTA. 



[ 625 ] SYNOVIAL MEMBRANES. 



Char. Eye single, cervical, rotatory organ 

 furnished with styles ; foot forked. 



Jaws each with a single tooth. 



Some of the species are furnished with 

 one or more so-called crests, which in some 

 appear to correspond to the calcar. 



S. haltica (PL 35. fig. 26). Body ovate; 

 rotatory lobes four ; st^^les four ; a single 

 median sessile crest. Marine ; length 1-108". 

 Phosphorescent. 



Three other species. 



BiBL. Ehrenberg, Infus. p. 436. 



SYNCRYPTA, Ehr.— A doubtful genus 

 of Volvocinese (Confervoid Algae), composed 

 of organisms consisting of a hyaline spherical 

 membrane (" gelatinous envelope," Ehr.) 

 enclosing a number of ovate green bodies 

 placed at the periphery and sending out a 

 pair of free vibratile cilia (only one, Ehr.) 

 from the surface of the envelope. Green 

 bodies not attenuated at the posterior extre- 

 mity- ; " no eye-spot." S. Volvox (PI. 3. fig. 

 14 6), globe 1-5/6" in diameter, green "ani- 

 malcules " 1-2880" long; aquatic, not ma- 

 rine. This object, which we have observed 

 in company with those represented in figs. 

 14 a, 31 and 32 of the same plate, is most 

 probably a Volvox in one of the stages of 

 conversion of an encysted spore (fig. 34) 

 into a perfect family-stock (fig. 24). See 

 Volvox. 



BiBL. Ehrenberg, Infus. p. 60. 



SYNCYCLIA, Ehr.— A genus of Diato- 

 macese. 



Char. Frustules cymbelliform, united in 

 circular bands, immersed in an amorphous 

 gelatinous substance. Marine. 



The nodules appear to be the same as 

 those of CymheUa. 



S. salpa (PI. 14, fig. 14). Frustules semi- 

 ovate, unstriated (ord. ilium.), commonly 

 six together, united into a ring ; endochrome 

 bright green. 



S. quaternaria. Frustules two or four 

 together ; endochrome yellow or reddish ; 

 length 1-860". 



BiBL. Ehrenberg, Infus. p. 233, Ber. d. 

 Berl. Akad. 1840. 32 ; Kiitzing, Sp. Alg. 61 . 



SYNDENDRIUM, Ehr.— A genus of 

 Diatomacese. 



Char. Frustules single, subquadrangular, 

 destitute of a median umbilicus ; valves un- 

 equal, slightly turgid, one smooth, the other 

 with numerous spines or little horns branched 

 at the ends situated upon the median 

 flat portion, the margins being free from 

 them. 



S. diadema. Frustules lanceolate ; spines 



five or six, bifurcate or tufted at the end, as 

 long as the frustules are broad. Breadth 

 1-1150". Found in Peruvian guano. 



BiBL. Ehrenberg, Ber. d. Berl. Akad. 

 1845. 155; Kiitzing, Sp. Alg. 141. 



SYNEDRA, Ehr.— A genus of Diatoma- 

 ceae. 



Char. Frustules prismatic, rectangular, or 

 curved; at first attached to a gelatinous 

 sometimes lobed cushion, subsequently 

 often becoming free; valves linear or lan- 

 ceolate. 



The valves usually exhibit a longitudinal 

 line, with a dilated median and two terminal 

 nodules; they are also generally covered 

 with transverse striae ; in some species the 

 median line and appearance of a median 

 nodule correspond to a clear space, free from 

 the transverse striae. 



Kiitzing describes sevent}^ species ; Smith 

 twenty-four as British. 



S. splendens, K. {S. radians, Sm.) (PI. 13. 

 fig. 23 a, h, c). Frustules elongated, in front 

 view dilated and truncate at the ends; 

 valves gradually attenuated from the middle 

 to the obtuse ends. Aquatic ; common ; 

 length 1-/0". 



Frustules radiate upon the cushion. 



S.fulgens {Licmophora fulg . K.) (PI. 13. 

 fig. 24). Frustules linear ; valves slightly 

 dilated in the middle and at the rounded 

 ends, arranged in a fan- shaped manner upon 

 the branched cushion. Marine; length 

 1-120". 



-S. capitata (PI. 13. fig. 25). Frustules 

 linear, truncate, ends slightly dilated ; valves 

 linear, ends dilated into a triangular head. 

 Aquatic; length 1-60". 



BiBL. Smith, Brit.Diat. i. 69; Kiitzing, 

 Sp. Alg. 40. 



SYNOVIAL MEMBRANES.— In minute 

 structure these resemble serous mem- 

 branes. 



They are sometimes furnished with appen- 

 dages, some of which contain fatty tissue ; 

 others abound in capillaries, and are met 

 with forming fringes w'here the svno^^al 

 membrane is attached to the articular carti- 

 lages. The latter consist of a basis of indi- 

 stinctly fibrous areolar tissue, covered by the 

 synovial epithelium, with a few fat-cells, 

 sometimes isolated cartilage-cells, and the 

 capillaries. Attached to their margins are 

 flattened, conical, stalked, smaller appendages 

 (fig. 720), seldom containing blood-vessels, 

 and composed of indistinctly fibrous areolar 

 tissue, with scattered cartilage-cells, and a 

 thick epithehal layer; while some of the 



2 s 



