SYNECIIOCOCCUS. 



[ 748 ] 



SYNTETHYS, 



tufted at the end, as loii": as the frustules 

 are broad. Breadth 1-1150". Found in 

 Peruvian guano. 



BiBL. Ehr. Ber. Berl. Ahtd. 1845, 155; 

 Kiitz. Sp. Ah/. 141; Pritchard, Infus. 8GG. 



SYNECHOCOC'CUS, Nag.— A genus of 

 Unicellidar Algae. 



Char. Cells minute, oblong, single or eon- 

 joined in rows of 2-4; dividing in one di- 

 rection only; endochrome seruginous or 

 yellowish. 



S. (enu/inosus (PI. 3. fig. SH). Common 

 on damp rocks and banks. (Rabenht. Alt/. 

 ii. 59.) 



SYxNE'DEA, Ehr.— A genus of Diato- 

 macepe. 



C/iar. Frustules prismatic, rectangular, 

 or curved ; at first attached to a gelatinous, 

 sometimes lobed cushion, subsequently often 

 becoming free; valves linear or lanceolate. 



The valves usually exhibit a longitudinal 

 line, with a dilated median and two termi- 

 nal 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 striffi. 



Species very numerous. 



S. radians, Sm. {splendens, K.) (PL 17. 

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

 view dilated and truncate at the ends ; 

 valves gradually attenuated from the mid- 

 dle to the obtuse ends. Freshwater ; com- 

 mon; length 1-70". Frustules radiate upon 

 the cushion. 



S. ftdf/ens (Linnophora fuhj. K.) (PI. 

 17. fig. 24). Frustules linear ; valves slightly 

 dilated in the middle and at the rounded 

 ends, arranged in a fan-shaped manner upon 

 tbe branched cushion. Marine ; length 

 ]-120". 



8. capitata (PI. 17. fig. 25). Frustules 

 linear, truncate, ends slightly dilated; valves 

 linear, ends dilated into a triangular head. 

 Freshwater ; length 1-GO". 



BiBL. Smith, Br. Diat. i. 69; Kiitz. 

 Sp. Ah/. 40; Rabenht. AI;/. i. 126; Gru- 

 now, M. M. Jn. xviii. KJG. 



SYN'GAMUS, Lieb.— Agenus of Nema- 

 toid Entozoa. S. frachcaJis is very common 

 in the trachea of poultry, producing the 

 "gapes." (Dujardin, i/f'/«H'/;^/(f',s, 260; Sie- 

 bold, Wiegmann^s Arch. 1835; Cobbold, 

 Paras?) 



SYNOVIAL MEMBRANES.— In minute 

 structure these resemble serous membranes. 



Synovial membranes are occasionally fur- 

 nished with appendages, some of which 



contain fatty tissue, others abound in capil- 

 laries and form fringes where the synovial 

 membrane is attached to the articular car- 

 tilages. The latter consist of a basis of 

 indistinctly fibrous connective tissue, co- 

 vered by the sj'novial e])ithelium, with a 

 few fat-cells, sometimes isolated cartilage- 

 cells, and the capillaries. Attached to their 

 margins are flattened, conical, stalked, 

 smaller appendages (fig. 715), seldom con- 

 taining blood-vessels, and composed of indi- 

 stinctly fibrous areolar tissue, with scattered 

 cartilage-cells, and a thick epithelial layer ; 

 while some of the smaller ones consist 

 almost entirely of epithelial cells or of 

 areolar tissue. 



Fig. 715. 





From he synoyial membrane of a finger-joint. 



A. Two appendages of the synovial ]irocesses. a, 

 areolar tissue in its axis; h, ipithelium of the free 

 margin : c, that eontinuons with the epithelium of the 

 processes; d, cartilage-cells. Magnified S.'iO diameters. 



B. Four ejiithelial cells froiQ the synovial membrane 

 of the Itnec-joiut, one of them with two nuclei. Magni- 

 fied 350 diameters. 



BiBL. Brinton, Todd's Cyd. An. ^- Bhi/s. 

 art. Serous Membranes ; Albert, Strieker's 

 Jlisf. iii. 



SYN'TETHYS, Forbes.— A genus of 

 Tunicate Mollusca, of the family Botryllidfe. 



Cliar. Mass sessile, gelatinous, forming a 

 single system ; animal sessile, ha^^ng simple 



